INTRALYMPHOCYTIC FREE CALCIUM AND MAGNESIUM IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS AND EFFECTS OF BLOOD PRESSURE AND VARIOUS ANTIHYPERTENSIVE AGENTS

1. Free Ca²⁺ (Ca²⁺]i) and Mg²⁺ (Mg²⁺]i) were measured in peripheral lymphocytes from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) at the age of 5, 7 and 17 weeks, from various antihypertensive agents-treated SHRSP, and from secondary hypertensive WKY. 2. At the age of 5 weeks, no difference was observed in systolic blood pressure (SBP), or lymphocyte Ca²⁺]i and Mg²⁺]i between SHRSP and WKY. At the age of 7 or 17 weeks, SBP and Ca²⁺]i of SHRSP were significantly higher than in WKY, and at the age of 17 weeks, Mg²⁺]i of SHRSP was significantly lower than in WKY. Further, Ca²⁺]i or Mg²⁺]i was positively or negatively correlated to SBP, and Mg²⁺]i was negatively correlated to Ca²⁺]i. 3. SBP of SHRSP fell significantly after antihypertensive treatment with calcium antagonist, angiotensin-converting enzyme (ACE) inhibitor or hydralazine for 40 days. Ca²⁺]i was significantly lower in calcium antagonist and hydralazine groups, and tended to be low in ACE inhibitor group. These four groups showed no difference in Mg²⁺]i. 4. After 40-day administration of N^G-nitro-l-arginine (l-NNA), WKY developed severe hypertension, but there were no significant differences in lymphocyte Ca²⁺]i and Mg²⁺]i between the l-NNA treated and non-treated groups. 5. These results suggested that increased lymphocyte Ca²⁺]i and decreased Mg²⁺]i observed in SHRSP are not only secondary to hypertension but possibly related to a basic genetic abnormality of divalent cation handling.