[The effects of isotheoline (IST) on the nonvascular smooth musculature]

The influence of IZT on nonvascular smooth musculature in experiments in vitro was studied: on isolated intestine of the rabbit, ileum of the guinea pig, an uterine horn of the rat and guinea pig, vas deferens of the rat; as well as in vivo: on an experimental model of bronchospasm of guinea pigs, induced by acetylcholine, histamine and serotonin. Isometric contractions were recorded, and in the experiments in vivo--the tonus of the bronchial smooth musculature by a piston recorder. The obtained results showed that in experiments in vitro IZT increased the dose dependent tonus of intestinal smooth musculature; inhibited predominantly at low concentrations like clonidine the contractions of vas deferens of the rat by low frequent field stimulation--0.1 Hz and its influence was weak in respect to contractions of this organ, induced by high frequent field stimulation (10 Hz); inhibited the contractions of vas deferens in response to exogenously administered NA. IZT inhibited only bronchoconstrictor effect of serotonin in experiments in vivo. It was established that the effects of IZT both in respect to the vascular and to the nonvascular smooth musculature were Ca++ dependent and were connected with pre- and postsynaptic alpha-adrenergic receptors.