Effects of calcium loading in DOCA-salt hypertensive rats.
The effects of oral calcium loading on blood pressure (BP) of DOCA (deoxycorticosterone acetate)-salt hypertensive rats (D-S rats) were investigated. Calcium loading was performed by adding 1% CaCl2 (calcium chloride) to the drinking water. Calcium loading attenuated the development of high BP in D-S rats, and at the end of a two week experiment, BP was 141 +/- 3 (calcium treated) vs. 174 +/- 7 mmHg (non-calcium treated) (p less than 0.01). However, calcium loading did not cause any changes in BP in normotensive rats. Further, in established D-S rats [after four weeks of DOCA and 1% NaCl (sodium chloride) treatment], calcium loading for 4 weeks also reduced BP [144 +/- 6 (calcium treated) vs. 181 +/- 4 mmHg (non-calcium treated), p less than 0.01, at the end of experiment]. With calcium treatment, there were no significant changes in sodium-water balance, plasma levels of epinephrine and norepinephrine, plasma renin activity, plasma aldosterone concentration and serum electrolytes both in developing and established D-S rats. The depressor mechanism of calcium loading was studied by observing vascular responsiveness to norepinephrine both in whole body and in hind limb preparations. Vascular reactivity in both developing and established D-S rats was significantly attenuated by calcium treatment. These results suggest that the antihypertensive effects of calcium treatment in D-S rats are mainly caused by attenuation of vascular reactivity.
Kageyama
Y
Y
Department of Internal Medicine, School of Medicine Keio University, Tokyo, Japan.
Suzuki
H
H
Arima
K
K
Kondo
K
K
Saruta
T
T
D000450:Aldosterone / Q000097:blood; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology*; D003900:Desoxycorticosterone; D004326:Drinking; D004837:Epinephrine / Q000097:blood; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000097:blood; D012964:Sodium / Q000652:urine; D014655:Vascular Resistance / Q000187:drug effects; D014882:Water-Electrolyte Balance / Q000187:drug effects
D003900:Desoxycorticosterone; D000450:Aldosterone; D012964:Sodium; D012083:Renin; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine