title: High calcium diet, different antihypertensive agents, and cytosolic free Ca2+ in spontaneously hypertensive rats.
abstract: Several studies have shown that increased dietary calcium decreases blood pressure (BP) in spontaneously hypertensive rats (SHR), but the underlying mechanisms are not fully understood. We compared the effects of a high calcium diet and different antihypertensive agents on BP and intracellular free Ca2+ concentration ([Ca2+]i) in lymphocytes of adult SHR. The calcium content of the normal chow was 1.1% and that of the high calcium chow was 2.5%. Antihypertensive drug treatments were performed by giving the animals trichlormethiazide (2 mg/kg/day), atenolol (25 mg/kg/day), and quinapril (10 mg/kg/day) in drinking water. Untreated SHR and normotensive Wistar-Kyoto (WKY) rats served as controls. After 14 weeks of study systolic BP (SBP) and [Ca2+]i in blood lymphocytes, measured with a fluorescent indicator quin-2, were higher in untreated SHR than in WKY rats. Trichlormethiazide, atenolol, quinapril, and the high calcium diet all decreased BP in SHR, but only quinapril and calcium-rich diet concurrently reduced [Ca2+]i. We conclude that the reduction in [Ca2+]i during high calcium intake does not result from decreased BP itself. If the changes in lymphocyte [Ca2+]i reflect Ca2+ metabolism in other tissues as well, especially in vascular smooth muscle, the normalization of [Ca2+]i may be involved in the BP-lowering mechanisms of oral calcium loading and angiotensin-converting enzyme (ACE) inhibition in genetic hypertension.
authors.affiliation: Department of Biomedical Sciences, University of Tampere, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Arvola
authors.forename: M
authors.initials: M
authors.lastname: Kähönen
authors.forename: H
authors.initials: H
authors.lastname: Mäkynen
authors.forename: H
authors.initials: H
authors.lastname: Wuorela
authors.forename: V
authors.initials: V
authors.lastname: Manninen
authors.forename: H
authors.initials: H
authors.lastname: Vapaatalo
authors.forename: I
authors.initials: I
authors.lastname: Pörsti
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001262:Atenolol / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004347:Drug Interactions; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D000077583:Quinapril; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D044005:Tetrahydroisoquinolines; D014237:Trichlormethiazide / Q000494:pharmacology*
chemical_list: D000959:Antihypertensive Agents; D002136:Calcium, Dietary; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; D001262:Atenolol; D014237:Trichlormethiazide; D000077583:Quinapril; D002118:Calcium