Sinoaortic baroreflex system and early pressure rise in renal hypertensive rabbits

Abstract

This was a study to determine if the sinoaortic baroreceptor reflex system of rabbits diminished or delayed the rise of arterial pressure during the initial development of renal hypertension. A method for inducing renal hypertension was chosen whereby the renal stimulus could be measured in conscious animals. One kidney was removed and the opposite 1 enclosed in a sterile latex capsule. Within 10-15 hr. fluid began to accumulate inside the latex capsule which produced a counterpressure, ERCP, on the kidney and this could be measured from the outside through a tube connected to the capsule. As increased ERCP developed, mean arterial pressure, MP, began to rise. On postoperative day 1 both pressures were elevated and they continued to rise during the subsequent week. Denervated animals showed a linear relationship between MP rise and the degree of renal stimulus. Their ratios of MP rise to renal stimulus were compared to those of rabbits with nerves intact but no significant differences were found either for the entire week or on separate days at matched values of renal stimulus. Thus, the rabbit sinoaortic reflex mechanism did not reduce the magnitude or rate of development of renal hypertension but it apparently began to reset as soon as MP rose and continued to do so throughout the week.