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 transmural pressure (myogenic response) of the isolated basilar artery and femoral artery from Rhesus monkeys. Whether or not spontaneous tone developed, a transmural pressure-diameter relation was determined after the equilibration period. Vessels were then constricted with a submaximal dose of prostaglandin-F2α (PGF2α; 1.23–2µM) and a flow-diameter relation (0–2,000µl/min) and a pressure-diameter (15–125cmH2O) relation were determined. Endothelium function was tested with the calcium ionophore A-23187 (1.0 µM). The vessels were then maximally dilated (papaverine, 100µM) and a passive pressure-diameter relation was determined. The responses of the basilar and the femoral arteries were markedly different. The basilar artery developed spontaneous tone, while the femoral artery did not. The basilar artery showed flow-induced constriction (P = 0.024), while the femoral artery dilated when flow was increased (P = 0.0005). The myogenic index of the two arteries during treatment with PGF2α was not different (P = 0.49) and the strength of the myogenic response was such that the diameter of both arteries stayed constant over the pressure range studied. We conclude that the responses to mechanical stimuli of the basilar artery and the femoral artery of the Rhesus monkey are markedly different.