A G(s)-coupled purinergic receptor boosts Ca2+ influx and vascular contractility during diabetic hyperglycemia

Abstract

Elevated glucose increases vascular reactivity by promoting L-type Ca(V)1.2 channel (LTCC) activity by protein kinase A (PKA). Yet, how glucose activates PKA is unknown. We hypothesized that a G(s)-coupled P2Y receptor is an upstream activator of PKA mediating LTCC potentiation during diabetic hyperglycemia. Experiments in apyrase-treated cells suggested involvement of a P2Y receptor underlying the glucose effects on LTTCs. Using human tissue, expression for P2Y(11), the only G(s)-coupled P2Y receptor, was detected in nanometer proximity to Ca(V)1.2 and PKA. FRET-based experiments revealed that the selective P2Y(11) agonist NF546 and elevated glucose stimulate cAMP production resulting in enhanced PKA-dependent LTCC activity. These changes were blocked by the selective P2Y(11) inhibitor NF340. Comparable results were observed in mouse tissue, suggesting that a P2Y(11)-like receptor is mediating the glucose response in these cells. These findings established a key role for P2Y(11) in regulating PKA-dependent LTCC function and vascular reactivity during diabetic hyperglycemia.