Effect of Low Dietary Calcium Intake on Blood Pressure and Pressure Natriuresis Response in Rats: A Possible Role of the Renin-Angiotensin System

Abstract

Dietary Ca is an important modulator of blood pressure in humans and rats. Since the kidney plays a key role in the pathogenesis of hypertension, the effects of a low Ca diet (0.01% Ca) on blood pressure and pressure natriuresis response were studied in normotensive Sprague-Dawley rats. In addition, a possible role of the renin-angiotensin system in the development of hypertension and an altered pressure natriuresis response resulting from low dietary Ca intake was examined. In the low Ca diet group, systolic blood pressure measured by the tail-cuff method was significantly higher than in the normal Ca diet group (1,1% Ca) 1 week after the diet (1 13.0 +/- 7.1 vs. 105.0 +/- 9.5mmHg, p < 0.05). After 4 weeks, the hypertension was more pronounced. Low dietary Ca intake significantly inhibited the water and sodium excretory responses to acute elevation of renal perfusion pressure by tightening an infrarenal aortic constriction. Treatment with an inhibitor of angiotensin-converting enzyme, captopril (30 mg/kg/day), completely abolished the elevation of blood pressure and attenuated the reduced pressure natriuresis response observed in Ca-deficient rats. Although plasma renin activity was not different between the low and normal Ca diet groups after the 2-week dietary regimen, the pressor response to angiotensin II was enhanced by 30% in the low Ca diet group and there was a significant difference in the pressor response between the two groups. These results suggest a possible involvement of the renin-angiotensin system in the development of hypertension and an inhibitory effect on the pressure natriuresis response caused by low dietary Ca intake, via an enhanced sensitivity to angiotensin II.

The Effect of Different Amounts of Calcium Intake on Bone Metabolism and Arterial Calcification in Ovariectomized Rats

“…A previous animal experiment using a hypertensive rat model reported that a high 2.5% Ca diet attenuated the development of hypertension or cardiac hypertrophy (39), and it was supported by the view that higher Ca supplementation reduces blood pressure by decreasing peripheral arterial resistance (40). Subsequently, elevating blood pressure has been considered as one of the risk factors of arterial calcification and stiffness (12,13). However, in this VDN rat model, we could not find any preventive effects of a high Ca intake on arterial Ca deposition.…”

“…According to several animal studies, an extraordinary low Ca intake around 0.01% induced an inhibitory effect on the pressure natriuresis response and increased sensitivity to the pressor response to angiotensin II, leading to the development of hypertension (12,13). Elevating blood pressure induced an arterial stiffening, reducing its distensibility, which was associated with an increased Ca content in the artery (14,15).…”

Mechanisms Involved in the Relationship between Low Calcium Intake and High Blood Pressure

“…Dietary calcium has been shown to have an effect on blood pressure in animal studies. Normotensive rats fed a free-calcium diet significantly increased their systolic blood pressure (SBP) between 15 to 35 mmHg in comparison with rats fed with normal calcium diet [4,5,6]. On the other hand, normotensive and hypertensive rats supplemented with calcium had significant lower values of SBP [7,8,9,10].…”

Association of dietary calcium intake and body fat with hypertension in Indian adolescents

“…I ntraventricular hemorrhage (IVH) often occurs in premature infants and results in increased morbidity and mortality in survivors [1]. Intrauterine infection may predispose to IVH through inflammation [2].…”

“…ow dietary calcium intakes are related to conditions other than bone health, such as hypertension, with possible involvement of renin-angiotensin system [1]. Objective of this study was to explore association of dietary calcium intake and body composition with blood pressure (BP) in 10 -14 year-old Indian adolescents.…”