Linked increased calcium and sodium in SHR of young age versus age-matched WKY

摘要

Background: Alterations in the metabolism of calcium and sodium have been implicated in the pathogenesis of primary hypertension. Calcium influx across the external cellular membrane in smooth muscle cells and cardiomyocytes plays a crucial role in the control of cellular excitation contraction and impulse propagation. Intracellular calcium and sodium concentrations are controlled by reversible binding to specific calcium binding proteins. The calcium and sodium flux across the external membrane is regulated by a calcium pump (calcium-magnesium ATPase), calcium channels, magnesium sodium anti-port and binding to the membrane. Material and methods: In this context, in aortic smooth muscle cells from 7 spontaneously hypertensive rats (SHR) of the Miinster strain (systolic blood pressure 182.4 +- 6.8 mmHg) and 7 normotensive rats (WKY, systolic blood pressure 116.5 +- 5.3 mmHg) aged 1-2 months, the intracellular calcium and sodium contents were measured under nearly in vivo conditions by electron-probe microanalysis. Measurements were performed in aortic cryosections 3 um thick. Results: The calcium content was 0.39 +-0.13 g/kg dry weight in SHR versus 0.21 +- 0.12 g/kg dry weight in WKY (means +- SD, p < 0.05), the sodium content was 8.92 +- 0.75 in SHR versus 6.74 +-0.71 g/kg dry weight in WKY (p < 0.05). Aortic smooth muscle cells from young SHR are characterized by markedly elevated intracellular calcium and sodium contents as compared with normotensive cells. Cellular calcium and sodium handling is disturbed in SHR aortic smooth muscle cells as it is in hypertensive blood cells. Conclusion: The increased calcium and sodium concentrations are a pathogenetic factor for the development of arteriosclerosis and hypertension.