Effects of felodipine on blood pressure and lymphocyte membrane characteristics in spontaneously hypertensive stroke-prone rats.
Adult spontaneously hypertensive stroke-prone rats (SHRSP) and age- and sex-matched Wistar-Kyoto rats (WKY) were treated with the calcium-channel antagonist felodipine for 2-4 weeks (1 mg/g in rat chow powder). Control rats of both strains were fed untreated chow. At the end of the treatment period we measured blood pressure, net potassium efflux and intralymphocytic calcium concentration. In the untreated rats the values for these parameters were significantly higher in SHRSP than in WKY. Felodipine treatment caused a reduction in the SHRSP values to WKY levels. We conclude that the high blood pressure of SHRSP results from an increase in membrane permeability to calcium. The resultant increase in intralymphocytic calcium concentration causes an increase in net potassium efflux via calcium-activated potassium channels. By reducing the membrane permeability to calcium with felodipine, these parameters were returned to normal or near-normal levels.
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Department of Physiology, University of Michigan, Ann Arbor 48109.
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D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D015736:Felodipine; D005260:Female; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D009568:Nitrendipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology*; D011919:Rats, Inbred Strains / Q000502:physiology*; D011921:Rats, Inbred WKY
D009568:Nitrendipine; D015736:Felodipine; D011188:Potassium; D002118:Calcium