ATP and norepinephrine contributions to sympathetic vasoconstriction of tail artery are altered in streptozotocin-diabetic rats

Sympathetic vasoconstriction is susceptible to diabetes, but contributions made by purinergic neurotransmission in this state have not been investigated. We aimed to evaluate sympathetic vasoconstriction contributions by ATP and norepinephrine in the tail artery from streptozotocin-diabetic rats by using isometric vascular rings. Tail arteries were isolated from rats made diabetic 3 mo earlier with streptozotocin (diabetic group), age-matched nondiabetic rats (nondiabetic injected), age-matched untreated animals (noninjected normal), and age-matched untreated animals in high glucose control Krebs solution (high glucose control). Responses to KCl (60 mM) or nerve stimulus trains of 1–100 impulses were identical in all groups. Electrical stimulation produced progressively greater contractions with increasing impulse numbers. These were partially reduced by suramin (100 μM, P2 antagonist), NF-279 (1 μM, P2X blocker), and phentolamine (2 μM, α-blocker). For purinergic antagonists, blockade was greater in diab...