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.