P2X(1) receptor-deficient mice establish the native P2X receptor and a P2Y6-like receptor in arteries. Mol Pharmacol 2002; 62: 1438–45

The contribution of P2 receptors to vasoconstriction of mouse mesenteric arteries was determined using wild-type (WT) and P2X1 receptor-deficient (KO) animals. ,-methylene ATP (,-meATP) and ATP evoked transient inward currents and con-strictions of WT mesenteric arteries. In contrast, ,-meATP (100 M) and ATP (100 M) failed to evoke responses in KO arteries from a range of vascular beds. Nerve stimulation (100 pulses at 10 Hz) evoked constrictions of mesenteric arteries. For WT arteries, the P2 receptor antagonist pyridoxalphos-phate-6-azophenyl-2-5-disulfonate (PPADS) (30 M) reduced the amplitude of response by 50%; the residual constriction was abolished by prazosin (0.1 M). In KO mice, vasoconstric-tion induced by nerve stimulation was reduced in amplitude by 50%, unaffected by PPADS, but was abolished by prazosin