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Topic:In Vitro Research

In vitro research involving horses refers to the study of equine cells, tissues, or biological molecules outside their normal biological context, typically in controlled laboratory environments. This research approach allows scientists to investigate cellular processes, molecular interactions, and the effects of various treatments without the ethical and logistical complexities of in vivo studies. In vitro studies contribute to understanding equine physiology, pathology, and pharmacology by providing insights into cellular responses to pathogens, drugs, and other stimuli. This page compiles peer-reviewed research studies and scholarly articles that explore various in vitro methodologies and their applications in equine science, including cell culture techniques, molecular assays, and drug efficacy testing.
Evidence of new cadmium binding sites in recombinant horse L-chain ferritin by anomalous Fourier difference map calculation.
Proteins    June 17, 1998   Volume 31, Issue 4 477-485 
Granier T, Comberton G, Gallois B, d'Estaintot BL, Dautant A, Crichton RR, Précigoux G.We refined the structure of the tetragonal form of recombinant horse L-chain apoferritin to 2.0 A and we compared it with that of the cubic form previously refined to the same resolution. The major differences between the two structures concern the cadmium ions bound to the residues E130 at the threefold axes of the molecule. Taking advantage of the significant anomalous signal (f" = 3.6 e-) of cadmium at 1.375 A, the wavelength used here, we performed anomalous Fourier difference maps with the refined model phases. These maps reveal the positions of anomalous scatterers at different locations...
Pharmacokinetics and pharmacodynamics of fenleuton, a 5-lipoxygenase inhibitor, in ponies.
Research in veterinary science    June 13, 1998   Volume 64, Issue 2 111-117 doi: 10.1016/s0034-5288(98)90005-4
Marr K, Marsh K, Hernandez L, Cunningham FM, Lees P.Leukotrienes, products of the 5-lipoxygenase pathway of arachidonic acid metabolism, possess properties consistent with their involvement in a range of inflammatory diseases. In this study the pharmacokinetics and pharmacodynamics of the selective 5-lipoxygenase inhibitor, fenleuton, have been examined in the horse. Orally administered fenleuton (four 5 mg kg(-1) doses, given once daily) was absorbed from the gastrointestinal tract, and penetrated readily into tissue cage exudate, the ratio of the plasma:exudate AUC0-48h being 0.90+/-0.02 (n=6). Ionophore-stimulated leukotriene (LT) B4 synthes...
CLoning of equine interleukin 1 alpha and equine interleukin 1 beta and determination of their full-length cDNA sequences.
American journal of veterinary research    June 12, 1998   Volume 59, Issue 6 704-711 
Howard RD, McIlwraith CW, Trotter GW, Nyborg JK.To clone equine interleukin 1 alpha (IL-1 alpha) and equine interleukin 1 beta (IL-1 beta) and determine their full-length cDNA sequences. Methods: The mRNA isolated from lipopolysaccharide-stimulated cultured equine monocytes was reverse transcribed, and a cDNA library was constructed in a lambda phage. The cDNA library was screened by means of plaque hybridization with radiolabeled human IL-1 alpha and IL-1 beta cDNA probes. The cDNA nucleotide sequences for equine IL-1 alpha and equine IL-1 beta were determined by use of the dideoxy chain termination technique. The cDNA sequences were analy...
Effect of tumor necrosis factor antibody given to horses during early experimentally induced endotoxemia.
American journal of veterinary research    June 12, 1998   Volume 59, Issue 6 792-797 
Barton MH, Bruce EH, Moore JN, Norton N, Anders B, Morris DD.To test efficacy of murine monoclonal, rabbit polyclonal recombinant equine or human tumor necrosis factor-alpha (rETNF or rHTNF, respectively) antibodies to inhibit native equine tumor necrosis factor (TNF) activity. Methods: 8 and 18 healthy adult horses for parts 1 and 2 of the study, respectively. Methods: In part 1, supernates from endotoxin-activated peritoneal macrophages were incubated with various dilutions of each rETNF antibody and subsequently tested for TNF activity. Serum was also obtained from a horse 1 hour after infusion with 20 ng of endotoxin/kg of body weight and was incuba...
Equine Embryo Transfer IV. Proceedings of the 4th International Symposium on Equine Embryo Transfer. Reims, France, 16-18 January 1997.
Equine veterinary journal. Supplement    June 6, 1998   Issue 25 6-112 
No abstract available
A conserved structural element in horse and mouse IGF2 genes binds a methylation sensitive factor.
Nucleic acids research    May 30, 1998   Volume 26, Issue 7 1605-1612 doi: 10.1093/nar/26.7.1605
Otte K, Choudhury D, Charalambous M, Engström W, Rozell B.The equine IGF2 gene has been cloned and characterised. It spans a 9 kb region, which is substantially less than the corresponding human gene. Three coding exons and three untranslated leader exons, all highly homologous to those in other species, were identified. Downstream of the polyadenylation site in exon 6, a dinucleotide repeat sequence was identified. Three putative promoters (P1-P3) were localised in the 5' region of the gene. RNase protection analysis revealed two active promoters in fetal tissues, P2 and P3, whereas P3 was the only promoter active in adult tissues. This represents a...
Equine infectious anemia virus transactivator is a homeodomain-type protein.
Journal of molecular biology    May 30, 1998   Volume 277, Issue 4 749-755 doi: 10.1006/jmbi.1998.1636
Willbold D, Metzger AU, Sticht H, Gallert KC, Voit R, Dank N, Bayer P, Krauss G, Goody RS, Rösch P.Lentiviral transactivator (Tat) proteins are essential for viral replication. Tat proteins of human immunodeficiency virus type 1 and bovine immunodeficiency virus form complexes with their respective RNA targets (Tat responsive element, TAR), and specific binding of the equine anemia virus (EIAV) Tat protein to a target TAR RNA is suggested by mutational analysis of the TAR RNA. Structural data on equine infectious anemia virus Tat protein reveal a helix-loop-helix-turn-helix limit structure very similar to homeobox domains that are known to bind specifically to DNA. Here we report results of...
Contribution of K+ channels and ouabain-sensitive mechanisms to the endothelium-dependent relaxations of horse penile small arteries.
British journal of pharmacology    May 30, 1998   Volume 123, Issue 8 1609-1620 doi: 10.1038/sj.bjp.0701780
Prieto D, Simonsen U, Hernández M, García-Sacristán A.1. Penile small arteries (effective internal lumen diameter of 300 600 microm) were isolated from the horse corpus cavernosum and mounted in microvascular myographs in order to investigate the mechanisms underlying the endothelium-dependent relaxations to acetylcholine (ACh) and bradykinin (BK). 2. In arteries preconstricted with the thromboxane analogue U46619 (3-30 nM), ACh and BK elicited concentration-dependent relaxations, pD2 and maximal responses being 7.71+/-0.09 and 91+/-1 % (n=23), and 8.80+/-0.07 and 89+/-2% (n=24) for ACh and BK, respectively. These relaxations were abolished by me...
Peculiarities of vitamin D and of the calcium and phosphate homeostatic system in horses.
Veterinary research    May 28, 1998   Volume 29, Issue 2 173-186 
Breidenbach A, Schlumbohm C, Harmeyer J.The aim of the present study was to investigate the importance of putative regulatory factors of the calcium (Ca) and inorganic phosphate (P(i)) homeostatic system in the horse. The concentrations of Ca, P(i), vitamin D metabolites, parathyroid hormone (PTH), the activity of the alkaline phosphatase (AP) and the concentration and binding properties of vitamin D binding protein (DBP) were measured in the plasma. In addition, the ability of the renal cortex to hydroxylate calcidiol into 24,25(OH)2D3 and 1,25(OH)2D3 was evaluated in vitro. The plasma concentration of Ca (3.2 +/- 0.15 mmol.L-1, N ...
The effect of propanediol on the morphology of fresh and frozen equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 80-84 doi: 10.1111/j.2042-3306.1997.tb05107.x
Bruyas JF, Martins-Ferreira C, Fiéni F, Tainturier D.Seventeen horse embryos recovered on the sixth day after spontaneous ovulation were; 1) washed in PBS (n = 6), 2) treated with 1.5 M 1-2 propanediol (n = 6) or, 3) frozen and thawed using 1.5 M propanediol as the cryoprotectant (n = 5). After treatment, the embryos were incubated for 6 h in medium before they were fixed, serially sectioned and examined microscopically to count the total numbers of interphase, mitotic and pycnotic nuclei. Significant differences were measured only in the mean proportions of pycnotic cells (+/- s.d.), both between the control (9.2 +/- 7.3%) and frozen-thawed emb...
Cumulus expansion, chromatin configuration and meiotic competence in horse oocytes: a new hypothesis.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 43-46 doi: 10.1111/j.2042-3306.1997.tb05098.x
Hinrichs K.When recovered from the follicle, horse oocytes may be categorised as having either a compact or an expanded cumulus. Cumulus expansion is strongly associated with follicle atresia. Oocytes with expanded and compact cumuli have similar proportions in the germinal vesicle stage when recovered from the follicle. However, during in vitro culture, a higher proportion of oocytes with expanded cumuli mature, and they do so more quickly, than do oocytes with compact cumuli. Using Hoechst 33258 to label chromatin, in the germinal-vesicle stage horse oocytes can be divided into those in which the nucle...
Treatment of equine oocytes with A23187 after intracytoplasmic sperm injection.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 51-53 doi: 10.1111/j.2042-3306.1997.tb05100.x
Kato H, Seidel GE, Squires EL, Wilson JM.In vitro matured horse oocytes with a first polar body (n = 68) were each injected with a single spermatozoon and divided into 2 groups: Group 1 oocytes were treated with 10 microM calcium ionophore A23187 for 5 min while Group 2 oocytes received no activation treatment. After culture in vitro for 2 days, significantly more oocytes treated with A23187 (5/24, 21%) cleaved than oocytes without activation treatment (2/44, 5%, P<0.05). All 7 cleaved zygotes from both treatment groups were transferred to recipient mares but no pregnancies resulted.
The effect of sucrose in the thawing solution on the morphology and mobility of frozen equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 94-97 doi: 10.1111/j.2042-3306.1997.tb05110.x
Huhtinen M, Lagneaux D, Koskinen E, Palmer E.Seventy-five embryos were collected 6 days after ovulation. Sixty embryos were frozen in straws using glycerol as the cryoprotectant in an automatic freezer. In Experiment 1 the freezing and thawing media were supplemented with 1.3 g/l PVP; in Experiment 2 the supplement was 5% FCS. The embryos were thawed for 30 s at +37 degrees C in a waterbath. In Experiment 1 glycerol was removed from 10 embryos in 6 steps. In 10 other embryos, glycerol and sucrose were both removed from the medium in 6 steps. After glycerol and sucrose removal, the embryos were stained with 4',6'-diamidino-2-phenylindole ...
Transfer of immature oocytes to a preovulatory follicle: an alternative to in vitro maturation in the mare?
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 54-59 doi: 10.1111/j.2042-3306.1997.tb05101.x
Goudet G, Bézard J, Duchamp G, Palmer E.In the mare, success rates for the in vitro maturation of oocytes are low. Accordingly, we attempted to determine if immature oocytes could be matured in vivo by injecting them into a preovulatory follicle. Groups of 3-9 oocytes collected from donor mares were transferred under ultrasound control into the preovulatory follicle of a recipient mare that was treated with crude equine pituitary gonadotrophin (CEG) to induce ovulation. Just before ovulation (34 h post treatment) the preovulatory follicle of the recipient mare was punctured to collect both the transferred and the indigenous oocytes ...
Cryopreservation procedures for Day 7-8 equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 98-102 doi: 10.1111/j.2042-3306.1997.tb05111.x
Young CA, Squires EL, Seidel GE, Kato H, McCue PM.Larger grade 1 or 2 (1 = excellent,.... 4 = degenerate) equine embryos that ranged in diameter from 300 to 680 microm and were recovered from mares on Day 7 or 8 after ovulation, were randomly assigned to 3 widely divergent cryopreservation treatments. Treatment 1 consisted of cooling from -6 degrees C to -35 degrees C at 0.5 degrees C per min followed by plunging into liquid nitrogen, with a one-step addition and a 4-step removal of 1.0 M glycerol. Treatment 2 (step-down equilibration) consisted of a 2-step addition of glycerol to 4.0 M followed by a decrease to 2.0 M prior to freezing, with ...
Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 88-93 doi: 10.1111/j.2042-3306.1997.tb05109.x
Ferreira JC, Meira C, Papa FO, Landin e Alvarenga FC, Alvarenga MA, Buratini J.Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were remov...
Comparison of different methods for the recovery of horse oocytes.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 47-50 doi: 10.1111/j.2042-3306.1997.tb05099.x
Alm H, Torner H, Kanitz W, Becker F, Hinrichs K.The object of this study was to compare 4 different methods of oocyte recovery from mares; 1) transvaginal follicle aspiration in vivo; 2) follicle aspiration in vitro; 3) oocyte recovery by isolation of follicles in vitro and 4) follicle scraping in vitro. Oocyte recovery was highest after follicle scraping (71.1%) and follicle isolation and rupture (61.3%). Follicle aspiration in vitro and in vivo yielded oocytes on 31.2% and 19.3% of occasions, respectively. The output of different types of cumulus-oocyte-complexes was different among the methods; the portion of compact cumulus-oocyte-compl...
Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 33-37 
Bézard J, Mekarska A, Goudet G, Duchamp G, Palmer E.The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles > or =5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicl...
Parentage testing of Day 10 equine embryos by amplified PCR analysis of microsatellites.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 69-71 doi: 10.1111/j.2042-3306.1997.tb05104.x
Guèrand M, Mahla R, Lagneaux D, Amigues Y, Palmer E, Bézard J.Paternity analysis was performed on the DNA of 21 equine embryos collected nonsurgically 10 days after ovulation from known mares, but involving 3 possible sires. After extraction, the DNA of each embryo was typed by radioactive PCR amplification using 10 characterised microsatellites; HMS 1, 2, 5, 6, 7 and 8 (Guérin et al. 1994) and HTG 3, 4, 6 and 10 (Marklund et al. 1994). The 21 dams and 3 sires were genotyped using DNA extracted from blood and amplified by PCR. After electrophoresis and autoradiography of the PCR products of the embryo and parents, the alleles of the embryo were compared...
Living fibroblast cells in the oviductal masses of mares.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 103-108 doi: 10.1111/j.2042-3306.1997.tb05112.x
Aguilar JJ, Woods GL, Miragaya MH, Olsen LM.The object of this experiment was to estimate the number and type of living cells in oviductal masses of mares. Oviducts of abattoir mares were dissected, divided into 3 sections, and flushed individually. Oviductal masses were recovered from 220 of 250 mares and from 389 of 500 oviducts. A greater number of masses was recovered from the left than the right oviducts. A higher percentage of masses was recovered from the ampullary-isthmic junction than from the ampulla or isthmus. The number of masses increased slightly with increasing mare age and was weakly correlated with the number of unfert...
Equine oocyte-cumulus morphology as affected by follicular size.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 38-42 doi: 10.1111/j.2042-3306.1997.tb05097.x
Mlodawska W, Okólski A.From the ovaries of 256 slaughtered mares a total of 1713 follicles were isolated from which 1641 (95.8%) oocytes were recovered (6.4/mare). A total of 564 follicles and oocytes were evaluated for the degree of vascularisation of the follicle wall, the appearance of the follicular fluid and the location and morphology of the cumulus-oocyte-complex. Follicles with a diameter of >10 mm displayed more numerous, well branched and more pronounced blood vessels than the smaller ones (4-10 mm diameter) and most of them contained clear, yellowish fluid with few granulosa cells. The percentage of oo...
Effect of anti-freeze protein (AFP) on the cooling and freezing of equine embryos as measured by DAPI-staining.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 85-87 doi: 10.1111/j.2042-3306.1997.tb05108.x
Lagneaux D, Huhtinen M, Koskinen E, Palmer E.Equine embryos recovered on Day 6 after ovulation were cooled to +4 degrees C, or frozen with AFP alone or together with glycerol. Twenty embryos (140-200 microm in diameter) were randomly assigned to 6 treatment groups. In the first 3 groups, the embryos were cooled from room temperature to +4 degrees C at a rate of 3 degrees C/min and warmed again at a rate of 32 degrees C/min in a programmable freezer. In the second 3 groups, the embryos were frozen using a standard protocol, stored in liquid nitrogen for 5-7 days and then thawed in a 37 degrees C waterbath. After cooling/warming or freezin...
Effects of follicular aspiration and flushing, and the genotype of the fetus on circulating progesterone levels during pregnancy in the mare.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 25-32 doi: 10.1111/j.2042-3306.1997.tb05095.x
Meintjes M, Graff KJ, Paccamonti D, Eilts BE, Paul JB, Thompson DL, Kearney MT, Godke RA.When aspirating ovarian follicles in pregnant mares to obtain oocytes for in vitro fertilisation (IVF), the effect of the manipulation on circulating concentrations of progesterone may be an important consideration in terms of the maintenance of pregnancy. The object of this study was to compare the effects of 3 different forms of transvaginal ultrasound-guided follicle aspiration (Treatment 1, no aspiration, n = 4; Treatment 2, aspirate only follicles > or =20 mm in diameter, n = 7; Treatment 3, aspirate all visible follicles, n = 7) on peripheral plasma progesterone concentrations between Da...
Evidence that surface proteins Sn14 and Sn16 of Sarcocystis neurona merozoites are involved in infection and immunity.
Infection and immunity    May 9, 1998   Volume 66, Issue 5 1834-1838 doi: 10.1128/IAI.66.5.1834-1838.1998
Liang FT, Granstrom DE, Zhao XM, Timoney JF.Sarcocystis neurona is the etiologic agent of equine protozoal myeloencephalitis (EPM). Based on an analysis of 25,000 equine serum and cerebrospinal fluid (CSF) samples, including samples from horses with neurologic signs typical of EPM or with histologically or parasitologically confirmed EPM, four major immunoblot band patterns have been identified. Twenty-three serum and CSF samples representing each of the four immunoblot patterns were selected from 220 samples from horses with neurologic signs resembling EPM and examined for inhibitory effects on the infectivity of S. neurona by an in vi...
Endotoxin treatment of equine infectious anaemia virus-infected horse macrophage cultures decreases production of infectious virus.
The Journal of general virology    May 6, 1998   Volume 79 ( Pt 4) 747-755 doi: 10.1099/0022-1317-79-4-747
Smith TA, Davis E, Carpenter S.Lentiviruses replicate in cells of the immune system, and activation of immune cells has been shown to modulate virus replication. To determine the effects of macrophage activation on replication of equine infectious anaemia virus (EIAV), primary horse macrophage cultures (HMCs) were established from 20 different horses, infected with an avirulent strain of EIAV, and stimulated with 5 microg/ml of bacterial endotoxin. Supernatants collected from HMCs were assayed for the presence of tumour necrosis factor (TNF-alpha) and for production of infectious virus. Results indicated that EIAV replicati...
In vitro propagation of Theileria annulata infected schizonts in different media supplemented with heterologous sera.
Indian journal of experimental biology    May 6, 1998   Volume 35, Issue 11 1175-1181 
Nichani AK, Sharma RD, Sarup S.Efficacy of medium RPMI-1640 (supplied by Gibco USA, Centron and Hi-media) supplemented with horse, donkey, sheep and goat sera was evaluated for in vitro propagation of Theileria annulata (Hisar) infected bovine mononuclear cells. The results were compared with the growth rate in RPMI-1640 supplemented with foetal bovine serum (Gibco). RPMI-1640 (Gibco) proved to be the best medium for in vitro cultivation of the parasite infected cells. Foetal bovine serum could be easily, safely and reliably substituted with goat and sheep sera in the growth medium. Horse and donkey sera also gave comparabl...
Isolation of Actinobacillus equuli from the oral cavity of healthy horses and comparison of isolates by restriction enzyme digestion and pulsed-field gel electrophoresis.
Veterinary microbiology    April 29, 1998   Volume 59, Issue 2-3 147-156 doi: 10.1016/s0378-1135(97)00188-0
Sternberg S.Swab samples were collected from the oral cavity of 174 horses in 10 farms and cultured selectively for Actinobacillus equuli. A. equuli could be isolated from 37% of all samples, varying between 12 and 88% in the different farms. Eight horses were sampled repeatedly for several days, with a variation in isolation frequency between 50 and 88%. Isolates were compared by restriction enzyme digestion and Pulsed-Field Gel Electrophoresis. A high degree of strain variability was found within each horse population as well as some variability over time between strains isolated from the same horse.
Evaluation of an in vitro degranulation challenge procedure for equine pulmonary mast cells. Hare JE, Viel L, Conlon PD, Marshall JS.Pulmonary mast cells (PMC) are important components of the inflammatory process in equine allergic lung diseases such as heaves. Very little, however, is known of the degranulation kinetics of these cells and thus, their pathophysiologic role remains largely speculative. The purpose of this study was to develop a repeatable protocol for in vitro equine PMC degranulation. Five mature horses (sex: 2 M, 3 F; age: 8.8 +/- 6.5 y), historically free of pulmonary disease and normal on clinical respiratory examination, arterial blood gas analysis, pulmonary mechanics testing and histamine inhalation c...
Oocyte transfer in mares.
Journal of the American Veterinary Medical Association    April 16, 1998   Volume 212, Issue 7 982-986 
Hinrichs K, Matthews GL, Freeman DA, Torello EM.Oocytes were collected from dominant preovulatory follicles of donor mares 24 hours after administration of human chorionic gonadotropin. Oocytes were incubated in vitro for 12 or 18 hours before transfer to recipient mares, representing maturation times after human chorionic gonadotropin administration of 36 and 42 hours, respectively. Pregnancy rates after transfer were 4 of 5 in the 36-hour group and 2 of 3 in the 42-hour group. The overall pregnancy rate achieved (6/8 mares) indicated that oocyte transfer may be useful clinically.
Plasma 5-hydroxytryptamine constricts equine digital blood vessels in vitro: implications for pathogenesis of acute laminitis.
Equine veterinary journal    April 16, 1998   Volume 30, Issue 2 124-130 doi: 10.1111/j.2042-3306.1998.tb04471.x
Bailey SR, Elliott J.Cumulative concentration response curves to 5-hydroxytryptamine (5-HT; 10(-10)-10(-4) mol/l) were constructed using isolated rings of equine digital, facial, tail and coronary arteries (endothelium intact). 5-HT was 17.7 and 41 times more potent as a vasoconstrictor of digital arteries than facial and tail arteries respectively. Removal of the endothelium increased the vasoconstrictor potency of 5-HT in the facial artery by 3.7-fold (P<0.05) but did not alter the sensitivity of digital arteries to 5-HT. Coronary arteries failed to contract to 5-HT. Coronary arteries pre-contracted with U440...