K. Horiuchi et al., LACK OF VASODILATORY RESPONSE IN SKELETAL-MUSCLE BLOOD-VESSELS OF AGED SPONTANEOUSLY HYPERTENSIVE RATS, Heart and vessels, 11(1), 1996, pp. 1-9
Regional hemodynamic responses to the vasodilators, hydralazine (1 mg/
kg, i.v.) and verapamil (0.1 mg/kg/min, i.v.), were examined in consci
ous Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR),
15 and 50 weeks of age, using the radioactive microsphere method. The
flow rates of heart and skeletal muscle in SHR were higher than those
in WKY, and the flow rates of liver, kidney, intestines, and skin in
SHR were lower than those in WKY. These differences between the region
al blood flow in WKY and SHR were observed in both aged and young rats
. The changes in organ blood flow induced by hydralazine and verapamil
were similar for WKY and SHR in most organs. Both drugs increased the
skeletal muscle blood flow in WKY and young SHR, but not in aged SHR,
that is, the skeletal muscle blood vessels in aged SHR lost their vas
odilatory response. These results suggest that, although a lack of vas
odilatory responses in the skeletal muscle vasculature of aged SHR may
be triggered by persistent hypertension, the vital organ vasculature
maintains its normal vasodilating capacity.