Is Hypercalcemic Diet A Possible Antidote To Oral Contraceptive-Induced Hypertension?

Administration of oral contraceptive (OC) has been associated with body fluid retention and in high doses over a long period, promotes hypertension (Oelkers 1996). This present investigation tests the hypothesis that the dietary calcium supplementation increases salt and water excretion in OC (norgestre/ethinylestradiol) treated 32 female albino rats randomly distributed into four (1-4) groups of 8 rats each: Control, OC-treated, OC-treated+ Calcium diet fed and Calcium diet fed only respectively. OC was administered to the appropriate groups by gavage. Experimental diet contained 2.5% calcium supplement. Plasma and urinary [Na+] [K+] were evaluated after 8 weeks of experimentation by flame photometry and plasma [Ca2+] by colorimetric method. OC-treatment induced a significant fall in urinary [Na+]. Water excretion was significantly reduced in these animals (control, 3.1±0.56 Vs OC-treated rats, 1.47±0.16; p< 0.05). OC-treated rats had significantly higher (p<0.05) plasma [K+] compared to control rats. Calcium supplementation induced increases in plasma [Na+], [K+] and augmented urinary Na+ excretion (OC-treated + Ca2+ diet Vs OC-treated only, p<0.05). Compared with the control rats, high Ca2+ diet fed rats exhibited significant increases in plasma [Nasup>+] and [K+] accompanied by significant decreases in urinary H20 excretion (p<0.05). These results strongly suggest that high dietary Ca2+ supplementation increases salt and water excretion in OC-treated rats and potentially moderates fluid retention and blood pressure in these animals, and may be of clinical significance in OC-induced abnormal fluid retention and perhaps OC-induced hypertension.