Soluble adenylyl cyclase (sAC) regulates calcium signaling in the vascular endothelium

The vascular endothelium acts as a selective barrier between the bloodstream and extravascular tissues. Intracellular [Ca²⁺]_i signaling is essential for vasoactive agonist-induced stimulation of endothelial cells (ECs), typically including Ca²⁺ release from the endoplasmic reticulum (ER). Although it is known that interactions of Ca²⁺ and cAMP as ubiquitous messengers are involved in this process, the individual contribution of cAMP-generating adenylyl cyclases (ACs), including the only soluble AC (sAC; ADCY10), remains less clear. Using life-cell microscopy and plate reader-based [Ca²⁺]_i measurements, we found that human immortalized ECs, primary aortic and cardiac microvascular ECs, and primary vascular smooth muscle cells treated with sAC-specific inhibitor KH7 or anti-sAC-small interfering RNA did not show endogenous or exogenous ATP-induced [Ca²⁺]_i elevation. Of note, a transmembrane AC (tmAC) inhibitor did not prevent ATP-induced [Ca²⁺]_i elevation in ECs. Moreover, l-phenylephrine-dependent constriction of ex vivo mouse aortic ring segments was also reduced by KH7. Analysis of the inositol-1,4,5-trisphosphate (IP₃) pathway revealed reduced IP₃ receptor phosphorylation after KH7 application, which also prevented [Ca²⁺]_i elevation induced by IP₃ receptor agonist adenophostin A. Our results suggest that sAC rather than tmAC controls the agonist-induced ER-dependent Ca²⁺ response in ECs and may represent a treatment target in arterial hypertension and heart failure.-Mewes, M., Lenders, M., Stappers, F., Scharnetzki, D., Nedele, J., Fels, J., Wedlich-Söldner, R., Brand, S.-M., Schmitz, B., Brand, E. Soluble adenylyl cyclase (sAC) regulates calcium signaling in the vascular endothelium.