Intraventricular Injection Of Vasopressin Receptor ¢ñ Blocker, Opc-21 268 On The Baroreceptor Reflex

According to the adjustment to baroreflex, CNS(central nervous system) adjust the sensitivity of reflex, range and level of blood. Make the cardiovascular function fit in with the need of organism in different condition. Many scholar consider that vasopressin antagonist as neural transmitter participate in the regulatory progress of harorefiex, It has been defined that vasopvessin antagonii increase the sensitivity of baroreflex in periphery But there is different formulation for centre to the regulatory function of haroretlex. In this study. observed the effect of renal sympathetic nerve activity in depressor reflex induced by phenvlcphrine by intravenous injection, after anesthetized rats were injected vasopressln antagonist OPC-2 1 268 in lateral ventricle, inquire into centre regulatory function of vasopressin in baroie flex.This experiments was performed on male Wistar rats weighting 280?330g. Rats were anesthetized by intraperitoneal injection of urethane, induced depressor reflex injected phenylephrine in remnoral vein, the rate of heart rate (HR) in depressor reflex an change value of renal sympathetic nerve activity (RSNA) with respect to the change value of average arterial pressure was index, observed the effect of sensitivity of baroreflex after the rats were injected OPC21268 in lateral ventricle. The study was divided into three parts:First. Observed the relation between the change of RSNA in baroreflex and blood pressure, HR. Second: Compare the depressor reflex of "Normal group"and Methyldopa group induced by phenylephrene respectively, defined ΔRSNA/ΔMAP or ΔHR/ΔMAP as main index of sensitivity of baroreflex; Third, Observed the change of sensitivity of baroreflex with time in depressor reflex after injected OPC-2 1268 in lateral. Ventricle inqjuire into the central regulatory function of Vasopressin in baroreflex.The results were as follow: 1, Grip the common carotid artery for 13-15 seconds, RSNA increased then I he blood pressure (BP) and HR; Injection of phenylephrine 8jig BP decreased than RSNA and HR increased. The change of HR was caused by the change ofRSNA, they had same various direction. This shows, RSNA can be regarded as main index of baroreflex. 2, After 3hours of rats given methyldopa 38mg, The rate of ΔRSNA/ΔMAP or ΔHR/ΔMAP were decreased 46% and 44.7% respectively with respect to normal group. The rate of ΔRSNA/ΔMAP and ΔHR/ΔMAP can be regarded as sensitive index of baroreflex.3, After the lateral ventricle injected OPC-21 268, the rate ofARSNA/AMAP and ΔHR/ΔMAP were decreased significantly, the inhibition could get to the top value after injection 45 inmates, It decreased 47.5 ±1.36% and 52.4±0.41% respectively prepare to before injection, R<0.001. It showed injection of OPC-2 1268 in lateral ventricle could inhibit baroreflex, it illustrated vasopressin had central facilitation function to the cause of baroreflex.