Effects of trimetaquinol on equine pulmonary vascular and airway smooth muscle.
Abstract: Trimetaquinol [TMQ: 1-(3’,4‘,5’-trimethoxybenzyl)6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline hydrochloride] a potential p-sympathomimetic bronchodilator (Iwasawa & Kiyomoto 1967), has been shown to be an effective tracheal smooth muscle relaxant in guineapigs (Iwasawa & Kiyomoto 1967; Brittain 1972; Brittain et a1 1970, 1976) and an inhibitor of experimental bronchospasm in guinea-pigs and cats (Brittain et a1 1970; Brittain 1972). In addition, clinical studies with TMQ indicated that the drug was an effective bronchodilator in mild to moderate asthma (Yamamura & Kishimoto 1968). It may be of value to determine the in vitro effects of bronchodilators on pulmonary vascular smooth muscle as well as airways (Hanna & Eyre 1979), since it is possible that, in vivo, inhaled bronchodilators may be distributed to the pulmonary vasculature, altering the vessel smooth muscle tone and consequently the pulmonary blood flow. This consideration plus the fact that TMQ has a non-selective 8-adrenergic action and some papaverine-like characteristics (Sato et a1 1967; Brittain 1972; Brittain et a1 1970, 1976) prompted these preliminary investigations of the action of TMQ on an integrated airway and a pulmonary vascular smooth muscle system from horse. Tissues from horse lung were employed because of the size of the pulmonary system, and the reported similarity of equine and human lung at the subgross and gross anatomical levels (McLaughlin et a1 1961; Tyler et al 1971). Pulmonary venous and tracheal smooth muscle was obtained from normal horses freshly killed in a local abattoir. Tissues were prepared according to the methods previously outlined (Hanna & Eyre 1978, 1979) and suspended in 10 and 20 ml organ baths with Webs-Henseleit solution aerated with 95 % 0 2 / 5 % CO, at 37 “C. The relaxant effects of TMQ were measured (isotonically) by first contracting the vein with an ED50 concentration of histamine (8.0 x M) and then adding increasing concentrations of TMQ in a cumulative fashion after the contractile response had reached maximum, Relaxation responses were expressed as percent inhibition of the histamine ED50 contraction. For tracheal studies, the relaxant effects of TMQ were measured (isometrically) by first pre-incubating the tissues with single concentrations of TMQ for 6 min, then challenging the tissues with an ED50 concentration of carbachol (5.0 x M).
Publication Date: 1979-12-01 PubMed ID: 43375DOI: 10.1111/j.2042-7158.1979.tb13682.xGoogle Scholar: Lookup
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- Journal Article
Summary
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The research article explores the effects of a drug called Trimetaquinol (TMQ) on the smooth muscle system of a horse’s lungs, specifically the airway and pulmonary vascular system. It suggests that TMQ functions by interacting with 8-adrenergic receptors in a non-selective manner and exerting effects similar to papaverine.
Drug Under Study: Trimetaquinol
- Trimetaquinol (TMQ) is a potential p-sympathomimetic bronchodilator that has demonstrated efficacy as a tracheal smooth muscle relaxant in guinea pigs and as an inhibitor of experimental bronchospasm in guinea pigs and cats.
- In clinical studies, TMQ proved to be an effective bronchodilator in mild to moderate cases of asthma.
- The drug exhibits a non-selective 8-adrenergic action and has some characteristics similar to those of papaverine, a vasodilator.
Purpose of the Study
- This research aims to determine the effects of bronchodilators on the pulmonary vascular smooth muscle, in addition to airways. This is important because inhaled bronchodilators may potentially alter pulmonary blood flow by changing the tone of the vessel smooth muscle.
- The study focuses on the action of TMQ on an integrated airway and a pulmonary vascular smooth muscle system from horses. Using horse tissues for this study allows a larger sample size due to their physiology and is relevant due to the similarities between equine and human lungs.
Methodology
- Pulmonary venous and tracheal smooth muscle were obtained from freshly killed normal horses at a local slaughterhouse. These tissues were prepared and suspended in organ baths with Webs-Henseleit solution, aerated with a mix of 95% O2 and 5% CO2 at 37 degrees Celsius.
- The study measured the relaxant effects of TMQ. To do this, they first contracted the vein with a concentration of histamine and then added increasing concentrations of TMQ after the contractile response reached its maximum.
- In tracheal studies, the authors pre-incubated tissues with single concentrations of TMQ for 6 minutes, followed by challenging the tissues with a concentration of carbachol.
Results and Interpretation
- The results were expressed as percent inhibition of the histamine ED50 contraction.
- Although specific results are not provided in the summary, it is implied that understanding the impact of TMQ on equine pulmonary vasculature and airway muscles could provide valuable insights applicable to human related bronchodilators.
Cite This Article
APA
Hanna CJ, Eyre P.
(1979).
Effects of trimetaquinol on equine pulmonary vascular and airway smooth muscle.
J Pharm Pharmacol, 31(12), 858-859.
https://doi.org/10.1111/j.2042-7158.1979.tb13682.x Publication
Researcher Affiliations
MeSH Terms
- Airway Resistance / drug effects
- Animals
- Carbachol / pharmacology
- Histamine / pharmacology
- Horses
- Humans
- In Vitro Techniques
- Isoquinolines / pharmacology
- Muscle Contraction / drug effects
- Muscle Relaxation / drug effects
- Muscle, Smooth / drug effects
- Muscle, Smooth, Vascular / drug effects
- Pulmonary Veins / drug effects
- Trachea / drug effects
- Tretoquinol / pharmacology
Citations
This article has been cited 1 times.- Bennett A, Jarosik C, Sanger GJ, Wilson DE. Antagonism of prostanoid-induced contractions of rat gastric fundus muscle by SC-19220, sodium meclofenamate, indomethacin or trimethoquinol. Br J Pharmacol 1980;71(1):169-75.
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