Vascular area with marked resistance elevation in one-clip, two-kidney renovascular hypertensive rats

Blood flow in the terminal aorta or superior mesenteric artery was recorded in conscious one-clip, two-kidney renovascular hypertensive rats and normal control rats with a chronically implanted electromagnetic flow probe. An indwelling catheter for direct measurement of arterial pressure was inserted into the terminal aorta in rats with a flow probe around the superior mesenteric artery. In the hindquarter area supplied by the terminal aorta, the elevation of vascular resistance in hypertensive rats in relation to normal rats was close to the average over the whole body. However, it was about 40% more intense than the average in the superior mesenteric area. Quantitatively, the hindquarter and superior mesenteric beds in hypertensive rats contributed about a quarter and a third of the decrease in total vascular conductance, respectively. Plots of superior mesenteric flow per body weight against arterial pressure at rest for 51 measurements in 9 hypertensive rats revealed an inverse relation between these two variables. These findings indicate that elevation of vascular resistance in the superior mesenteric area and probably the splanchnic area in general play an important role in one-clip, two-kidney renovascular hypertension.