THE CARDIOVASCULAR REACTIONS MEDIATED TPA AND TAMOXIFEN IN SPINAL CORD OF CONSCIOUS RATS

Intrathecal administration (ith)of phorbol 12-myristate(TPA),an activator of protein kinase C,(31.24,26.5, 125 and250ng/10μg)to conscious rats proeduced a marked dose-denpendent pressor effect without significanchange in heart rate (HR).Intrathecal administration of tamoxifen (3.125,6.5 andl00μg/μl), one of the inhibitors of protein kinase C, produced amarked dose-dependent hypotensive effect.Intrathecal injection of exogenous DBcAMP(12.5,25,50and 100μh/10μl)also incresed the mean arterial blood pressure(mABP)and markedly lowered HR.It was further observed that, based on the effect of DBcAMP(25μg/10μl),the pressor effect of fourdoses of TPA can be augmented. The results indicate that TPAin spinal cord may exert hypertensive effect via activation of PKCand tamoxifen may exert a hypotensive effect via inhibition of PKC,in addition, the pressor effect ofTPA could be augmented by preadministration of DBcAMP.