Effect of membrane domains in the Na+/H+ exchanger localization and function.

ZAVALA MR; GODOY COTO J,; LONGARZO L; BERNASCONI A; MATÉ SM; VILLA ABRILLE MC

Online

Congreso; Reunión anual 2021 "Descubriendo los engranajes fisiológicos desde la evolución a la traslación"; 2021

Sociedad Argentina de Fisiología

The plasma membranes of eukaryotic cells contain specific domains (MD) ?e.g., caveolae- in which key signal transduction proteins are localized. The Na+/H+ exchanger (NHE1), an integral membrane protein, is involved in the maintenance of intracellular pH. We postulate here that a preferential membrane partition of NHE1-into/out of MD- is critical for their function.Objective: Evaluate the organization of plasma membranes and the role of MD in the regulation of NHE1 activity. Methods: In cardiomyocytes isolated from normotensive, Wistar, and spontaneously hypertensive rats, SHR, it was determined: the structure of the membranes; NHE1 activity (ammonium pre-pulse method); expression of MD marker proteins, flotilin1 (F1) and caveolin3 (C3); the treatment with 2.5mM methyl-β-cyclodextrin (MβCD) was used for evaluating the effect of MD disruption).The data are expressed as mean ± SEM. Either an unpaired Student?s t-test or One-Way ANOVA were used to compare groups. A p < 0.05 was considered statistical significance.Results: Localization of F1 and C3 in light fractions of the sucrose gradient was used as MD markers. NHE1 was only found in the MD of Wistar´ cardiomyocytes. MβCD destabilized MD in cardiomyocytes of both rat strains (shifting both F1 and C3 to the bottom of the gradient), promoting, in Wistar, the translocation of NHE1 out of MD and increased maximal NHE1-mediated proton efflux [JH+ (mmol/L/min): 2.88±0.27, n=6; vs control 1.80±0.18, n=6, *p