Effects of various anaesthetics and relaxants on vascular smooth muscle
Pasch, T.; Renkl, F.
Der Anaesthesist 28(8): 390-397
1979
ISSN/ISBN: 0003-2417 PMID: 495921 Document Number: 150833
The effects of various injectable anesthetics and relaxants on the pressure-diameter relations of isolated segments of the rat tail artery were studied in vitro. The wall of the vessel contains about 75% smooth muscle fibers. Measurements were made before and after the induction of maximum constriction of the vascular segments produced by 1 mg/ml noradrenaline . When added to pure Tyrode's solution all the agents used did not markedly influence the pressure-diameter curves. The noradrenaline-induced constriction of the vessels was inhibited to varying degrees. Thiopentone caused the diameter to increase by 50%. Pentobarbitone increased the diameter .apprx. 15%. Administration of methohexitone was followed by lesser relaxation of the arterial smooth muscle causing a maximum increase in diameter of 7%. After alphathesin (CT 1341) and propanidid, the arterial segments dilated about 20% after etomidate and 4-hydroxybutyrate about 10%. The muscle relaxants suxamethonium and d-tubocurarine induced dilations of 10-15%, alcuronium and pancuronium induced dilations of < 5%. Apparently the dilatation of peripheral resistance vessels seen after the administration of narcotics and relaxants is not exclusively due to a neurally mediated inhibition of the vascular tone. The direct action of the substances on the vascular smooth muscle may often contribute to their complex hemodynamic effects.