Intracellular free Ca2+ and basal Mn2+ influx in cultured aortic smooth muscle cells from spontaneously hypertensive and normotensive Wistar-Kyoto rats.
Numerous studies investigating the possible role of altered Ca2+ homeostasis in hypertension have compared resting and agonist-stimulated intracellular free Ca2+ ([Ca2+]i) in cultured aortic smooth muscle cells from spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. However, such studies have not given consistent results. Differences in the method used to load cells with the Ca(2+)-sensitive indicator fura-2 have been investigated here as a possible source of variability between studies. We also describe the adaptation of a fluorescence technique for the assessment of basal Ca2+ permeability in SHR and WKY through the measurement of Mn2+ influx. The results are consistent with the hypothesis that basal Ca2+ influx is elevated in cultured aortic smooth muscle cells from SHR compared to those from WKY. However, this was not reflected as a significant difference between the two strains in basal or angiotensin II (200 nmol/L)-stimulated [Ca2+]i. Furthermore, this result was not dependent on the protocol used to load cells with fura-2. Hence, measurement of bulk [Ca2+]i does not appear to be the most sensitive parameter for altered Ca2+ homeostasis in SHR. Other compartments of the cell may better reflect altered Ca2+ fluxes in hypertension and are discussed in this work.
Monteith
G R
GR
Department of Pharmacy, University of Sydney, NSW, Australia.
Kable
E P
EP
Roufogalis
B D
BD
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005456:Fluorescent Dyes / Q000008:administration & dosage; D016257:Fura-2 / Q000008:administration & dosage; D007425:Intracellular Membranes / Q000378:metabolism*; D008297:Male; D008345:Manganese / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism*; D011921:Rats, Inbred WKY / Q000378:metabolism; D012016:Reference Values; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D005456:Fluorescent Dyes; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D008345:Manganese; D002118:Calcium; D016257:Fura-2