The surface morphology and ultrastructure of renal arterial smooth muscle cells in patients with renovascular hypertension.

The surface and internal ultrastructure of renal arterial smooth muscle cells were investigated in 3 patients with renovascular hypertension. The most characteristic features of the surface pathology in hypertrophied smooth muscle cells consisted of various degrees of surface defects, including both extensive loss of surface details and an irregular thickening and disruption of the basement membrane, which was widely separated from the plasma membrane by a clear space. Ultrastructural changes include the appearance of highly lobulated nuclei, multinucleation, disorganization of myofilaments and increased numbers of rough-surfaced sarcoplasmic reticulum and mitochondria, which are usual manifestations of cellular hypertrophy. These results suggest that ionic movement across the cell membranes, particularly of Ca2+, is probably abnormal in hypertrophied smooth muscle cells. This may result in functional disorders of hypertensive arteries.