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Histochemical and functional evidence for a cholinergic innervation of the equine ureter.
Abstract: The distribution of acetylcholinesterase (AChE)-positive nerve fibers and cells, as well as the effects of acetylcholine (ACh) on ureteral smooth muscle and small resistance arteries were investigated in the equine ureter by means of histochemical, classic organ baths and myograph techniques. AChE-positive nerve fibers were widely distributed throughout the ureteral wall forming muscular, subepithelial and perivascular nerve plexuses, whose density was highest at the intravesical ureter. AChE-positive nerve cells were also identified grouped as adventitial or intramural ganglia. ACh increased concentration-dependently both the frequency of phasic contractile activity and basal tone of the isolated intravesical ureter, the pD2 values being 6.31 +/- 0.18 and 6.59 +/- 0.13, respectively. The ACh-induced motor effects in ureteral smooth muscle were blocked by atropine, giving pIC50 values of 8.58 +/- 0.08 and 9.68 +/- 0.05 for phasic activity and tone, respectively. Hexamethonium only inhibited ACh-evoked contractile activity at the highest concentration used. ACh elicited a potent endothelium-dependent relaxation of equine ureteral resistance arteries precontracted with 40 mM K-PSS, the pD2 value being 7.94 +/- 0.07. This relaxant response was abolished in the presence of the nitric oxide (NO) inhibitor, NG-nitro-L-arginine (L-NNA), the blockade being reversed by subsequent incubation with the NO exogenous substrate, L-arginine. The ACh-induced relaxation was competitively antagonized by atropine (pA2 = 10.05 +/- 0.18). The present results suggest the existence of a rich cholinergic innervation in the equine ureter which controls both ureteral smooth muscle and resistance arteries motor activity through the muscarinic effects of ACh. In addition, the ACh relaxant response in the ureteral resistance arteries seems to be mediated by NO.
Publication Date: 1994-05-01 PubMed ID: 7912246DOI: 10.1016/0165-1838(94)90177-5Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research studies the presence and effects of acetylcholinesterase-positive nerve fibers and cells in the equine ureter, and how acetylcholine influences the function of ureteral smooth muscle and resistance arteries. The research findings suggest a robust cholinergic innervation in the equine ureter, which controls the motor activity of both the ureteral smooth muscle and resistance arteries, mediated in part by nitric oxide.
Histochemical Analysis
- The study used histochemical techniques to explore the distribution of acetylcholinesterase (AChE)-positive nerve fibers and cells in the equine ureter.
- These AChE-positive nerve fibers were found throughout the ureteral wall, forming muscular, subepithelial, and perivascular nerve plexuses, with the highest density at the intravesical ureter.
- AChE-positive nerve cells were also identified and grouped into adventitial or intramural ganglia.
Functional Analysis
- Further to the histochemical analysis, the study used classic organ baths and myograph techniques to investigate the effects of acetylcholine (ACh) on ureteral smooth muscle and small resistance arteries.
- ACh was shown to increase both the frequency of phasic contractile activity and the basal tone of the isolated intravesical ureter, evidenced by pD2 values.
- The ACh-induced motor effects were blocked by atropine, with pIC50 values for phasic activity and tone, which indicates antagonistic activity of atropine on the ACh-induced effects.
Role of Nitric Oxide
- The study observed that ACh evoked a strong endothelium-dependent relaxation in pre-contracted equine ureteral resistance arteries, a response associated with the pD2 value.
- This response was stopped in the presence of the nitric oxide (NO) inhibitor, NG-nitro-L-arginine (L-NNA), and reversed by incubation with the NO exogenous substrate, L-arginine, suggesting that NO mediates this relaxant response.
- The ACh-induced relaxation was also competitively antagonized by atropine, providing further evidence of the role of cholinergic innervation in modulating ureteral function.
Conclusion
- From the findings, this research suggests that there is a rich cholinergic innervation in the equine ureter that controls both ureteral smooth muscle and resistance arteries motor activity via the muscarinic effects of ACh.
- In addition to this, the relaxant response ACh induces in the ureteral resistance arteries is likely mediated by NO.
Cite This Article
APA
Prieto D, Simonsen U, Martín J, Hernández M, Rivera L, Lema L, García P, García-Sacristán A.
(1994).
Histochemical and functional evidence for a cholinergic innervation of the equine ureter.
J Auton Nerv Syst, 47(3), 159-170.
https://doi.org/10.1016/0165-1838(94)90177-5 Publication
Researcher Affiliations
- Departamento de Fisiología, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain.
MeSH Terms
- Acetylcholine / pharmacology
- Acetylcholinesterase / analysis
- Animals
- Arginine / analogs & derivatives
- Arginine / pharmacology
- Arteries / innervation
- Atropine / pharmacology
- Biomarkers / analysis
- Cholinergic Fibers / physiology
- Cholinergic Fibers / ultrastructure
- Female
- Hexamethonium
- Hexamethonium Compounds / pharmacology
- Horses / anatomy & histology
- Male
- Muscle Contraction / drug effects
- Muscle, Smooth / drug effects
- Nerve Tissue Proteins / analysis
- Nitric Oxide / physiology
- Nitroarginine
- Peristalsis / physiology
- Ureter / blood supply
- Ureter / innervation
Citations
This article has been cited 4 times.- Bayraktar Z, Albayrak S. Sexual intercourse as a new option in the medical expulsive therapy of distal ureteral stones in males: a prospective, randomized, controlled study. Int Urol Nephrol 2017 Nov;49(11):1941-1946.
- Fernandes VS, Ribeiro AS, Martínez P, López-Oliva ME, Barahona MV, Orensanz LM, Martínez-Sáenz A, Recio P, Benedito S, Bustamante S, García-Sacristán A, Prieto D, Hernández M. Hydrogen sulfide plays a key role in the inhibitory neurotransmission to the pig intravesical ureter. PLoS One 2014;9(11):e113580.
- Tomiyama Y, Wanajo I, Yamazaki Y, Murakami M, Kojima M, Shibata N. Functional muscarinic cholinoceptors in the isolated canine ureter. Naunyn Schmiedebergs Arch Pharmacol 2003 Apr;367(4):348-52.
- Hernández M, Barahona MV, Bustamante S, García-Sacristán A, Orensanz LM. A2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission. Br J Pharmacol 1999 Feb;126(4):969-78.
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