Plasmalemmal vacuolar type H+-ATPase (pmV-ATPase) is decreased in microvascular coronary endothelial cells (MCEC) from an insulin dependent diabetic model (BBd). Academic Article uri icon

abstract

  • Complications of diabetes involve abnormalities in blood flow regulation, microvascular proliferation and angiogenesis. Because intracellular pH (pHin) regulates cell growth, secretion, and cell motility/ migration, we examined if MCEC from the spontaneously diabetic BB rat (BBd) have altered pHin regulation. Cells from BBd and non-diabetic (BBn) rats were grown on glass cover slips and were intracellularly loaded with the pH fluorescent indicator SNARF-I. The steady-state pHin was significantly lower in the BBd than in BBn by ca. 0.1 pH unit regardless of the HCO3- concentration, suggesting that the differences were not due to HCO3--transport mechanisms. Acid loading experiments revealed similar levels of acidification in both cell types with BBn cells recovering faster than BBd, regardless of the presence or absence of Na+ and HCO3-. There were no differences in buffering capacity between BBn and BBd cells. In the absence of Na+, proton fluxes (JH+; mM/min) were two-fold higher in BBn man in BBd and were suppressed by V-H+-ATPase inhibitors. The data suggest that a dysfunction of pmV-ATPase is important in diabetes.

author list (cited authors)

  • Rojas, J. D., Wesson, D. E., Meininger, C. J., Wu, G., & Martinez-Zaguilan, R.

publication date

  • March 1998