The effects of vasoactive drugs on halothane inhibition of contractions of rat mesenteric lymphatics.

The effects of halothane on alpha-adrenergic receptors, beta-adrenergic receptors, and the process of Ca++ dependent contractions on rat mesenteric lymphatics were examined. Halothane depressed the contraction rate of mesenteric lymphatics but did not effect the increase in lymphatic contraction rate caused by noradrenaline (an alpha-agonist). The depressant effect of halothane on the contraction rate was also not antagonized by propranolol (a beta-blocker), but was partly reversed by CaCl2. These findings suggest that the depressant effect of halothane on the lymphatic contraction rate derives not from blocking lymphatic alpha-receptors or stimulating lymphatic beta-receptors but rather by halothane inhibition on the process of Ca++ dependent lymphatic contractions.