Effect of Mg deficiency on blood pressure in rats treated with cadmium.
Forty male STD-Wistar rats, weighing about 210 g on the average, were divided into two dietary groups. These were further subdivided into the following eight groups: 1) control rats fed the normal diet (N rats: group #1), N rats treated with 0.1 mg Cd (group #2), 0.5 mg Cd (group #3), and 1.0 mg Cd (group #4); 2) Mg-deficient rats (D rats: group #5), D rats treated with 0.1 mg Cd (group #6), 0.5 mg Cd (group #7), and 1.0 mg Cd (group #8). Before Cd treatment the rats were given the normal diet or the Mg-deficient diet for 14 consecutive days day -14). Subcutaneous injection of 0.1 ml of cadmium chloride (CdCl2) in the backs of the animals given a normal diet or a Mg-deficient diet at the three doses of 0.1, 0.5, and 1.0 mg/kg body was performed twice a day (12-h intervals) (time-zero) for 7 consecutive days and then these animals were maintained without Cd treatment for an additional period of 20 days (+28 days). Body weight gain in Mg-deficient rats (D rats) was significantly decreased. The effects of Cd treatment in the rats fed the normal diet (N rats) were also significant. Mg deficiency enhanced the decreased body weight gain in D rats treated with Cd on day 24 though no enhancement of the decreased food consumption in those rats was observed. Mg deficiency lowered the blood pressure in rats and this response was more pronounced in D rats treated with Cd. The increased urinary Na excretion and the decreased water retention were not observed in the D rats; this response was not pronounced in the D rats treated with Cd. These results suggest that an enhancement of the decreased blood pressure in Cd-treated rats by the Mg deficiency is not responsible for the decreased water retention. Ca concentration in the heart and aorta of D rats was within the same range as that of N rats. Mg deficiency increased Ca concentration in the heart and aorta of the D rats treated with 0.5 and 1.0 mg Cd though Cd itself did not affect the Ca and ATP concentrations, Ca and Mg balance (Ca/Mg), and heart weight in the heart of N rats. These results suggest that Mg deficiency may increase the overload of Ca in the heart and aorta of D rats treated with Cd, which may in turn lead to enhancement of the Cd-induced cardiotoxic effects.(ABSTRACT TRUNCATED AT 400 WORDS)
Nishiyama
S
S
Department of Environmental and Occupational Health, Kochi Medical School, Japan.
Saito
N
N
Konishi
Y
Y
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism / Q000652:urine; D006128:Growth; D008275:Magnesium Deficiency / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000652:urine
D002104:Cadmium; D012964:Sodium; D002118:Calcium