INTRACELLULAR PH MAPPING WITH SNARF-1 AND CONFOCAL MICROSCOPY .2. PH GRADIENTS WITHIN SINGLE CULTURED-CELLS

Using the pH-sensitive dual-emission fluorophore, carboxy-seminaphthorhodafluor-1 (SNARF-1) coupled with a laser-scanning confocal microscope system it is now possible to map intracellular pH. We have applied this combination to investigate the pH levels and distribution within single isolated cultured proximal tubule, bovine aortic endothelial and rat aortic smooth muscle cells. The majority of cells showed a uniform cytosolic pH. However, pH gradients were evident between the cytosol and nuclear regions with the nuclear regions having a predominantly higher pH than the cytosol. High concentrations of nigericin removed this gradient and indicated that active control of intranuclear pH by the nuclear membrane occurred, possibly via the K+/H+ exchanger.