Interaction of calcium channel blockers (CCBs) with histamine and 5-hydroxytryptamine in aorta from normal and diseased rats.
The present study attempts to investigate the interaction of calcium channel blockers (CCBs) with histamine (H) and 5-hydroxytryptamine (5-HT) in rat isolated aortic strip preparations. In preparations obtained from rats chronically treated with various CCBs the contractile responses to H were completely blocked suggesting that this may be due to inhibition of the voltage-dependent channels and inositol 1,4,5-triphosphate induced release of calcium from intracellular stores. The decreased contractions of the aortic strip preparations with 5-HT obtained from rats chronically treated with various CCBs implies a decrease in 5-HT receptor density. DOCA-saline hypertensive rats chronically treated with various CCBs showed variable responses to H and 5-HT suggesting that these changes may be due to different isoforms of L-type calcium channels. In L-thyroxine-treated preparations or those simultaneously treated with L-thyroxine and CCBs the responses to H were abolished and those to 5-HT were partially blocked with decrease in maxima which could be secondary to the primary effect on the heart and to generalised reduced senstivity of the rat aorta.
Bhugra
P
P
Department of Pharmacology, Pramukhswami Medical College, Karamsad.
Gulati
O D
OD
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003900:Desoxycorticosterone; D006632:Histamine / Q000494:pharmacology*; D006973:Hypertension / Q000139:chemically induced* / Q000503:physiopathology; D006980:Hyperthyroidism / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D012701:Serotonin; D003900:Desoxycorticosterone; D006632:Histamine