[Involvement of calmodulin in realization of vasoconstrictive effects of serotonin and norepinephrin].

ABSTRACT

Possible involvement ofcalmodulin in adrenergic and serotoninergic regulation of vascular contractility has been studied. Calmodulin inhibitors trifluoperazine and W-13 suppress vasoconstriction of the rat aorta in response to norepinephrine, serotonin, and serotonin 5HT1A- and 5HT2A-receptor agonists (8-OH-DPAT and DOI, respectively) and do not affect the vasodilatory effect of 5HT1B-, 5HT2B-, and 5HT4-receptors. The force of aorta contraction in response to 8-OH-DPAT increases after the activation of calcium entry through voltage-gated Ca2+-channels. This effect is not related to non-specific activation of alpha1-adrenoceptors, since it is realized in the presence of prazosin. The inhibitor of calmodulin-dependent myosin light chain kinase KN93 decreases the vasoconstrictive response in response to norepinephrine and serotonin by only 20%. Calmodulin inhibitors slightly decrease aortic constriction in response to endothelin-1, vasopressin, angiotensin II, and KCl. Trifluoperazine does not suppress vasoconstriction induced by the G-protein activator AlF4(-). It is assumed that the target of trifluoperazine and W-13 is calmodulin interacting directly with alpha1-adrenoceptors and serotonin 5HT1A- and 5HT2A-receptors.