The elevation of the cytoplasmic calcium ions in vascular smooth muscle cells in SHR--measurement of the free calcium ions in single living cells by lasermicrofluorospectrometry.

We have developed an accurate and sensitive system for the measurement of cytoplasmic free calcium concentrations ([Ca++]i) of a single cell by using UV-laser and Indo-1. By this method, we made the first successful measurement of [Ca++]i of single living vascular smooth muscle cells. [Ca++]i in spontaneously hypertensive rats was elevated and maintained after the 6th passage culture. However, [Ca++]i in Goldblatt hypertensive rats was not elevated. Thus, these results suggest that the maintenance of high [Ca++]i levels of vascular smooth muscle cells in spontaneously hypertensive rats is genetically regulated and that it is one of the mechanisms for hypertension.