RESPONSES TO MECHANICAL STIMULI OF ISOLATED BASILAR AND FEMORAL ARTERIES OF THE RHESUS-MONKEY ARE DIFFERENT

The present study aimed to determine regional differences in diameter response to mechanical stimuli such as flow (shear stress) and transmu ral pressure (myogenic response) of the isolated basilar artery and fe moral artery from Rhesus monkeys. Whether or nor spontaneous tone deve loped, a transmural pressure-diameter relation was determined after th e equilibration period. Vessels were then constricted with a submaxima l dose of prostaglandin-F-2 alpha (PGF(2 alpha); 1.23-2 mu M) and a fl ow-diameter relation (0-2,000 mu l/min) and a pressure-diameter (15-12 5 cmH(2)O) relation were determined. Endothelium function was tested w ith the calcium ionophore A-23187 (1.0 mu M). The vessels were then ma ximally dilated (papaverine, 100 mu M) and a passive pressure-diameter relation was determined. The responses of the basilar and the femoral arteries were markedly different. The basilar artery developed sponta neous tone, while the femoral artery did not. The basilar artery showe d flow-induced constriction (P 0.024), while the femoral artery dilate d when flow was increased (P = 0.0005). The myogenic index of the two arteries during treatment with PGF(2 alpha) was not different (P = 0.4 9) and the strength of the myogenic response was such that the diamete r of both arteries stayed constant over the pressure range studied. We conclude that the responses to mechanical stimuli of the basilar arte ry and the femoral artery of the Rhesus monkey are markedly different.