Intracellular free calcium and ionized plasma calcium during mineralocorticoid-induced blood pressure increase in man.
Intracellular free calcium is considered to play a key role in vascular smooth muscle contraction. Platelet-free intracellular and plasma total and ionized calcium were assessed during mineralocorticoid-induced blood pressure increase in eight normotensive subjects receiving 0.8 mg fludrocortisone per day for 6 weeks. Blood pressure rose within 1 week and showed a further increase up to the 6th week. Plasma noradrenaline and renin activity (PRA) showed a decrease after 1 week and remained suppressed throughout the study. Ionized plasma calcium fell during mineralocorticoid treatment without any significant changes in total plasma calcium. Intracellular free calcium markedly increased after 1 week and decreased towards control levels thereafter. Previous studies have shown that after 1 week of fludrocortisone administration total peripheral resistance is still normal or even subnormal, whereas it is increased after 6 weeks. Therefore, the initial increase in intracellular free calcium, if also present in arteriolar smooth muscle cells, does not appear to be directly related to the final elevation of total peripheral resistance.
Haller
H
H
Department of Internal Medicine, Freie Universität Berlin, Federal Republic of Germany.
Thiede
M
M
Lenz
T
T
Lüdersdorf
M
M
Harwig
S
S
Distler
A
A
Philipp
T
T
D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000097:blood*; D005438:Fludrocortisone / Q000494:pharmacology*; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000139:chemically induced; D008297:Male; D009638:Norepinephrine / Q000097:blood; D012083:Renin / Q000097:blood; D014655:Vascular Resistance / Q000187:drug effects
D012083:Renin; D002118:Calcium; D005438:Fludrocortisone; D009638:Norepinephrine