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 iCa^2-1was increased as compared to those from WKY rats (146 ± 14 and 112 ± 6.0 nm, respectively, P <. 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, jCa²⁺was found to be higher in SHR than in WKY rats (149 ± 23 and 89 ± 12 nm, respectively, P <. 05). The finding that jCa²⁺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 jCa²⁺is not a phenomenon generalized to all cells of this model of genetic hypertension.