Impaired Intestinal Calcium Transport in the Spontaneously Hypertensive Rat
The spontaneously hypertensive rat (SHR) exhibits a variety of abnormalities in its handling of calcium (1–3) and phosphorus (4,5) and calcium supplementation has been shown to reduce its arterial blood pressure (3,6). The relationship between disturbed calcium and phosphorus metabolism and hypertension, however, remains unclear. Several investigators have studied intestinal calcium transport in the SHR and have reported increased (7,8), unchanged (9) or decreased (10) absorption compared with its genetic control, the WistarKyoto rat (WKY). In these studies, Ca2+ absorption has been determined by means of intestinal perfusion (10) or in situ uptake (8) in vivo,everted gut sacs in vitro (7,9,10), or by balance studies (8). The variety of experimental systems employed may in part explain the diversity in these findings. We have recently addressed this issue utilising the modified Ussing apparatus (11) which permits continuous monitoring of tissue viability and the study of active intestinal calcium transport under electrically controlled conditions.
KeywordsShort Circuit Current Ussing Chamber Intestinal Perfusion Intestinal Calcium Transport Renal Phosphate Excretion
Unable to display preview. Download preview PDF.
- 2.G.L. Wright, and G.O. Rankin, Concentrations of ionic and total calcium in plasma of four models of hypertension. Am. J. Physiol. 243: H365 (1982).Google Scholar
- 3.D.A. McCarron, N.N. Yung, B.A. Ugoretz, and S. Krutzik, Disturbances of calcium metabolism in the spontaneously hypertensive rat. Hypertension 3 (suppl. I): I - 162 (1981).Google Scholar
- 7.M.A. Toraason, and G.L. Wright, Transport of calcium by duodenum of spontaneously hypertensive rat. Am. J. Physiol. 241: G344 (1981).Google Scholar
- 8.K. Lau, J. Zikos, J. Spirnak, and B. Eby, Evidence for an intestinal mechanism in hypercalciuria of the spontaneously hypertensive rat. Am. J. Physiol. 247: E625 (1984).Google Scholar
- 9.N. Stern, D.B.N. Lee, V. Silis, F.W. Beck, L. Deftos, S.C. Manolagas, and J.R. Sowers, Effects of high calcium intake on blood pressure and calcium metabolism in young SHR. Hypertension 6: 639 (1984).Google Scholar
- 11.M.W. Walling, and D.V. Kimberg, Active secretion of calcium by adult rat ileum and jejunum in vitro. Am. J. Physiol. 225: 415 (1973).Google Scholar
- 13.S.G. Schulz, and R. Zalusky, Ion transport in isolated rabbit ileum, short circuit current and Na+ fluxes. J. Gen. Physiol. 47: 567 (1964).Google Scholar
- 15.D.A. McCarron, P.A. Lucas, B. Lacour, R.J. Shneidman, and T. Drüeke, Blood pressure development of the spontaneously hypertensive rat following concurrent manipulations of dietary Ca2+ and Na+ : relation to intestinal Ca2+ fluxes. J. Clin. Invest. (in press).Google Scholar