Calcium reactivity and antagonism in portal veins from spontaneously hypertensive and normotensive rats.
Reactivities of portal veins from spontaneously hypertensive rats (SHR) and normotensive controls (Wistar Kyoto, WKY) at 5-7 and 15-17 weeks of age were compared. Systolic blood pressures were not different at 5-7 weeks but those of SHR were significantly elevated (177 +/- 4 mmHg) (1 mmHg = 133.322 Pa) at 15-17 weeks. Spontaneous activity, frequency, and tension were greater in SHR for both age groups. Young SHR were more sensitive to K+ at 5-7 weeks but less sensitive at 15-17 weeks than age-matched WKY rats. Sensitivity to Ca2+ in a K+-depolarizing medium was higher in SHR than in WKY for both age groups. Maximum tension responses to K+ or Ca2+ were greater in SHR. The Ca2+ channel antagonists nifedipine, nitrendipine, and nisoldipine were potent inhibitors of both noradrenaline- and K+-induced responses but did not show differences in inhibitory activity between WKY and SHR.
D000367:Age Factors; D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011169:Portal Vein / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction / Q000187:drug effects
D002121:Calcium Channel Blockers; D011188:Potassium; D002118:Calcium