Abstract:
The effects of ginkgolide B on the carotid sinus baroreflex(CSB)were studied in the perfused isolated carotid sinus of 30 anesthetized Sprague-Dawley male rats.The results were as follows.(1)By perfusing with ginkgolide B(0.1,1,10 μmol/L),the functional curve of the baroreflex was shifted to the right and upward.There was a marked decrease in peak slope(PS)and reflex decrease(RD)in mean arterial pressure(P<0.01),while the threshold pressure(TP),equilibrium pressure(EP)and saturation pressure (SP)were significantly increased(P<0.05,P<0.01).Among the functional parameters of CSB,the changes in PS,RD,TP,EP and SP were dose-dependent.(2)Pretreatment with Bay K8644(500 nmol/L),an agonist of L-type calcium channel,completely eliminated the effects of ginkgolide B(1 μmol/L)on the CSB.(3)Pretreatment with tetraethylammonium(TEA,1 mmol/L),an inhibitor of potassium channel,completely abolished the above effects of ginkgolide B(1 Iμmol/L)on the CSB.These results suggest that ginkgolide B inhibits the CSB in anesthetized rats,which iS mediated by decreased calcium influx and increased potassium efflux in baroreceptor nerve endings.