Cytosolic Calcium in T Lymphocytes From the Spontaneously Hypertensive Rat

To gain further insight into the possible generalized nature of intracellular calcium-related alterations in hypertension we measured free cytosolic calcium (iCa2+) in lymphocytes obtained from the spleen and the blood of the spontaneously hypertensive rat (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats. By monitoring Fura-2 fluorescence at an excitation wavelength of 340 nm and an emission wavelength of 510 nm we estimated; Ca2+. In peripheral lymphocytes from the SHR iCa2+ was increased as compared to those from WKY rats (146 +/- 14 and 112 +/- 6.0 nm, respectively, P less than .025). In contrast, in lymphocytes obtained from the spleen, iCa2+ was not different between SHR and WKY rats (93 +/- 7.0 and 96 +/- 8.0 nm, respectively). When spleen cells were subjected to selective B lymphocyte depletion to generate a preparation of predominantly T lymphocytes, iCa2+ was found to be higher in SHR than in WKY rats (149 +/- 23 and 89 +/- 12 nm, respectively, P less than .05). The finding that iCa2+ is elevated in peripheral lymphocytes and spleen cells subjected to B cell depletion but not in untreated spleen cells indicates that T, but not B, lymphocytes have increased iCa2+ in the SHR. This observation may be related to existing evidence that T lymphocyte function is impaired in the SHR. An increase in iCa2+ is not a phenomenon generalized to all cells of this model of genetic hypertension.