Vascular pressure-flow analysis in normal and hypoxemic spontaneously hypertensive rats.

The pressure-flow relationship of the autoperfused subclavian vascular bed was compared in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) after spinal cord transection. Studies were performed under normoxemic and hypoxemic conditions. In adult SHR, vascular resistance was greater relative to WKY under both conditions. In young (8 week old) SHR vascular resistance was consistently greater over a wide range of perfusion pressures compared to young WKY rats when blood oxygen content was normal. Vascular resistance was not different between young SHR and WKY when the animals were hypoxemic. The results demonstrated that elevated vascular resistance in adult SHR was independent of oxygen availability and supraspinal nerve function; however, in young SHR elevated vascular resistance was dependent upon oxygen availability, although independent of supraspinal nerve function.