(055) LRRC8A-VRAC Controls Superoxide Anion Flux in Diabetic Vasculogenic Erectile Dysfunction

Abstract

Abstract Introduction Erectile dysfunction (ED) may be an early marker for cardiovascular diseases, and it is often associated with an hypercontractility of the corpus cavernosum (CC) as a consequence of increased reactive oxygen species (ROS), which favors the flaccid state of the penis. Leucine Rich Repeat Containing 8 (LRRC8A) Volume Regulated Anion Channels (VRACs) regulates Nox1 and modulates the extracellular production of superoxide anion (O2•-). Downregulation of LRRC8A is associated with decreased production of O2•- and we have demonstrated improved relaxation and reduced contraction of the pudendal artery in LRRC8A knockout mice. Objective We hypothesized that the role of LRRC8A in contractile responses to phenylephrine (PE) and electrical field stimulation (EFS) in the CC of diabetic mice would be exaggerated compared to that in normal mice. Methods To test this hypothesis, the CC of diabetic (dbdb-/-) mice was mounted in a myograph, and contraction elicited by PE or EFS was performed in the presence of apocynin (non-selective NOX inhibitor), GKT137831 (NOX1/4 inhibitor) and montelukast (LRRC8A inhibitor). In LRRC8A KO dbdb-/- mice, contractions to PE and EFS were obtained in the absence or in the presence of GKT137831. Results In the CC, the maximal contraction to PE was increased in diabetic animals, and in the presence of 3 mM of apocynin, the contractile response was markedly diminished in both control and diabetic mice. The LRRC8A inhibitor, montelukast, significantly reduced PE-induced contraction of the CC reaching maximal contraction of 69 + 7% and 65 + 10% in the control and diabetic group, respectively, compared to the contraction in the absence of the inhibitor. In the presence of the Nox1/Nox4 inhibitor, GKT137831, the contraction elicited by PE was reduced only in the diabetic group (68 + 9% of the maximal contraction), whereas in the control group this reduction was not significant (82 + 14% of the PE-maximal contraction). In the LRRC8A KO dbdb-/- mice, the contraction to EFS was similar to dbdb-/-, however, GKT137831 reduced the contraction to EFS with lesser magnitude of inhibition in the LRRC8A KO dbdb-/- mice (35% of inhibition) compared to dbdb-/- mice (50% of inhibition), suggesting that the participation of O2•- in the contractile response was reduced by the lack of functional LRRC8A. Conclusions LRRC8A modulates the contractile response of the CC induced by α-adrenergic stimulation and in diabetes, this may be associated with O2•- production, which plays a role in the development of ED. Inhibition of LRRC8A may be a therapeutic target to prevent hypercontractility of arteries and CC in vasculogenic ED. Disclosure No.