AJP - Heart and Circulatory Physiology, Vol 251, Issue 5 984-H990, Copyright © 1986 by American Physiological Society
Effect of hypertensive rat plasma on ion transport of cultured vascular smooth muscle
W. W. Magargal and H. W. Overbeck
We layered fresh, unprocessed plasma from healthy rats with early (less
than or equal to 7 days) or benign, chronic (greater than 3 wk) one-kidney,
one-clip hypertension and from paired one-kidney normotensive control rats
over confluent primary-cultured rat aortic smooth muscle cells. Plasma from
all rats increased cellular ouabain-sensitive 86Rb+ uptake and sodium
content and decreased ouabain-insensitive 86Rb+ uptake compared with
uptakes and content in the presence of balanced salt solution (P less than
0.01). Cells incubated in the presence of plasma from rats with early (P
less than 0.02) or chronic hypertension (P less than 0.01) had
significantly reduced ouabain-sensitive 86Rb+ uptake when compared with
cells incubated in normotensive plasma, but their intracellular Na+
contents were not lower. We no longer detected this uptake difference when
chronic hypertensives drank 0.9% NaCl instead of water. Plasma from
hypertensive rats also altered ouabain-insensitive 86Rb+ uptake by the
cultured cells. These findings of this new, reproducible, and specific
assay system support the hypothesis that plasma factors inhibit the
membrane sodium-potassium pump in vascular smooth muscle cells in this form
of hypertension. The abnormality occurs in both early and chronic stages,
but may not be related to sodium intake. The data also provide evidence for
plasma factors in hypertension altering membrane K+ permeability.
