Activation of Cav1.2 and BKCa is involved in the downregulation of caffeine-induced contraction in mice mesenteric arteries.

AIMS: Caffeine is a methylxanthine with multiple actions in vascular smooth muscle cells (VSMCs), including the increase in the intracellular Ca2+ (iCa2+) concentration by the activation of ryanodine receptors (RyRs). The present study aimed at investigating the participation of Ca2+-influx through different Ca2+-channels on the transient contraction (TC) induced by caffeine in mice mesenteric arteries.

MAIN

METHODS

Second-order of mesenteric arteries was isolated from male Swiss mice. Vessels without functional endothelium were stimulated with caffeine (10 mM). The caffeine-induced TC was evaluated after the incubation of artery rings for 30 min with the following drugs: nifedipine (10 μM), a Cav1.2 blocker; 2-aminoethoxydiphenyl borate (2-APB; 10 μM) and ruthenium red (RuR; 10 μM), transient receptor potential (TRPs) channels blockers; capsazepine (10 μM) and HC067047 (10 μM), TRPV1 and TRPV4 antagonists, respectively; paxilline (1 μM), a selective BKCa blocker; and SKF-96365 (30 μM), an Orai blocker. Ca2+-fluorescence measurements were also performed on the investigated arteries.

KEY FINDINGS: The TC induced by caffeine was partially dependent on Ca2+-influx. However, the blockage of Cav1.2 increased the TC while reduced the iCa2+ signal. Similar results were observed after the blockage of TRPs or BKCa. Therefore, caffeine promoted Ca2+-influx via TRPs and Cav1.2, and hyperpolarization through the activation of BKCa, inducing negative feedback of TC.

SIGNIFICANCE: Our results indicate an alternative mechanism for the control of VSMCs contraction in resistance arteries. The evidence of the negative feedback of contraction via TRP-Cav1.2-BKCa provides a new perspective for understanding the mechanism involved in the vascular responses triggered by caffeine.