The effects of thiopentone on isolated dog peripheral arterial strips [TIYOPENTONUN IZOLE KOPEK PERIFERIK ARTER SERITLERI UZERINE OLAN ETKILERI]

Abstract

In this study the effects of thiopentone on isolated dog peripheral arteries, and the contributions of various factors on these effects were investigated. Besides, whether endothelium modulates the effects of thiopentone on arteries and any receptor mediates these effects were also studied. The responses taken from dog renal, femoral and mesenteric arteries were recorded on a polygraph isometrically. Thiopentone (10-5-3x10-4 M) caused dose related contractions in arterial strips; while it increased the contractions in the arterial strips that were precontracted submaximally with phenylephrine (3x10-7, 10-6 M), and inhibited the maximal contraction induced by phenylephrine (10-5 M). It caused a relaxing effect on contractions that were obtained by KCl (30 mM). 10-4 M and 3x10-4 M thiopentone inhibited the calcium induced contraction in calcium free potassium depolarizing solution in a dose related manner. Pharmacological antagonists did not produce any significant alterations on the effects of thiopentone. The contractions produced by thiopentone were not different in, the endothelium denuded and endothelium intact arterial strips. It was found that, the contractions caused by thiopentone were potentiated by the presence of phenylephrine (3x10-7, 10-6 M). These findings suggest that thiopentone has contradictory effects on the influx of calcium into cells according to the contractile state of the arteries. The effect of thiopentone on arteries is not specific. Besides it seems impossible that the contractile effect of thiopentone on arterial strips depends on the decreased release of endothelium derived relaxing factor and/or on the increased release of endothelium derived constricting factor.