Intracellular Na+ and Ca2+ activities in aortic smooth muscle cells from spontaneously hypertensive rats

Abstract

Elevations of intracellular Na+ and Ca2+ in essential hypertension have up to now only been demonstrated in blood cells. Therefore, intracellular Na+ and Ca2+ activities were determined in cultured aortic smooth muscle cells from nine spontaneously hypertensive rats of the Münster strain and from nine normotensive Wistar rats. Intracellular ion activities were determined by ion-selective electrodes. In muscle cells from spontaneously hypertensive rats intracellular Na+ activity was markedly elevated (P less than 0.01), whereas intracellular Ca2+ was not significantly different. This points to the preponderance of genetic causes for the elevation of intracellular Na+, whereas the disturbances in cellular Ca2+ metabolism may additionally require humoral factors to become manifest.

Intracellular Na+ and Ca2+ in aortic smooth muscle cells after enzymatic isolation in spontaneously hypertensive rats

“…On the whole, the results reported above together with earlier findings [1] suggest the action ofa humoral factor in the spontaneously hypertensive rat. Further investigations are necessary to identify this humoral factor.…”

“…It was shown that the changes in intracellular free Ca 2+ and Na +, which can be demonstrated in red blood cells from essentially hypertensive and from spontaneously hypertensive rats, are modified in cultured aortic smooth muscle cells from spontaneously hypertensive rats. Whereas intracellular Na + is more markedly elevated in cultured smooth muscle cells than in red blood cells from spontaneously hypertensive rats, conversely intracellular free Ca 2+ was shown to be not significantly elevated in aortic smooth muscle cells from spontaneously hypertensive rats [1]. With regard to these results the question arises as to what extent the discrepancies to the findings in red blood cells were caused by the absence ofhumoral factors in the culture medium, since the cultured aortic cells have not been exposed to any hormonal factors specific to one of the rat strains in the artificial medium.…”

“…In earlier studies the changes of intracellular electrolyte composition in red blood cells and in aortic smooth muscle cells from spontaneously hypertensive rats were compared [1]. It was shown that the changes in intracellular free Ca 2+ and Na +, which can be demonstrated in red blood cells from essentially hypertensive and from spontaneously hypertensive rats, are modified in cultured aortic smooth muscle cells from spontaneously hypertensive rats.…”

Intracellular vascular muscle Ca2+ modulation in genetic hypertension.

“…Evidence for an inverse correlation of plasma Ca 2+ and blood pressure has been reported in humans 13 and animals. 14 There is evidence for increased Ca 2+ in erythrocytes 15 and platelets of hypertensive humans. 16 Recent data from our laboratory suggest that a differential action of nitrendipine and related dihydropyridines might be found in SHR versus Wistar-Kyoto (WKY) rat vascular muscle because of Ca 2+ channel differences.…”