A close association between vasoconstrictor-mediated uracil and lactate release by the perfused rat hindlimb

1. Angiotensin II (5 nM) increased perfusion pressure, O2 uptake and the release of lactate, uracil and uric acid from the perfused rat hindlimb. The release of all three substances was greatest 5 min after commencement of angiotensin II infusion and then decreased over the next 20 min to reach a plateau value that was approx. 2.5-fold basal values. Following removal of angiotensin, pressure, O2 uptake as well as lactate, uracil and uric acid release each returned to pre-infusion (basal) values. 2. Cyanide (1 mM) when added during angiotensin II (5 nM) infusion blocked the pressor effect and completely inhibited all O2 uptake. Cyanide (1 mM) also inhibited the angiotensin-induced increase in uric acid, uracil and lactate release, but the effects differed. Whereas uric acid release remained inhibited throughout the cyanide infusion, uracil and lactate release were only temporarily interrupted and a secondary release of both ensued. 3. Nitroprusside (0.5 mM) when added during angiotensin II (5 nM) infusion blocked pressure and O2 uptake. Lactate and uracil release were partly blocked and returned to pre-infusion (basal) values. However uric acid release was totally blocked and no release occurred when nitroprusside was present with angiotensin II. 4. Combined data showed a significant correlation (r = 0.831; P less than 0.001) between effluent lactate and effluent uracil. 5. It is concluded that lactate and uracil release which increase markedly during vasoconstriction of the hindlimb reflect an association between glycolysis and uracil nucleotide turnover within the same tissue, possibly vascular smooth muscle.