The effect of chronic hypertension on skin blood flow.

Long term hypertension damages the microvasculature of the eye and kidney. We measured skin blood flow by laser Doppler in 22 Spontaneously Hypertensive Rats (SHR) as compared to 22 non-hypertensive Wistar-Kyoto (WKY) rats over a one year time span to see if the cutaneous microvasculature is affected by chronic hypertension. Sites of measurement included the back, leg, and tail, areas with a predominantly nutritive perfusion, and the plantar surface of the paw, which has a large contribution of large arterioles and venules (AV). Over the one year measurement period, there was no appreciable change in blood flow in the WKY animals. There was no change in basal blood flow in either rat strain. In contrast, the SHR rats showed a steady progressive decline in thermally stimulated skin blood flow reserve at all sites: The largest decline was at the paw with a rate of fall of about 2.4% per month. Skin blood flow reserve falls in response to chronic hypertension. The rate of fall is greater at sites with significant AV perfusion than at nutritive sites.