Alterations in the extracellular matrix of the myocardium in essential hypertension.

Hypertension produces myocyte hypertrophy and increases the extracellular matrix. In order to determine the composition of the extracellular matrix we studied the hearts from 14 hypertensive patients by immunohistochemistry using antibodies against collagen I, III, IV and V, fibronectin, myoglobin, muscular specific actin, Factor VIII, CD 34 and vimentin. The myocardium showed a focal increase in fibronectin, collagen I and III and diffuse deposition of laminin, collagen IV and V. Cells positive for vimentin, Factor VIII and CD 34 were also increased, but with considerable variation from case to case. We found no relation between matrix variation and the degree of hypertension or the time elapsed from the beginning of the disease. We conclude that the main role of the matrix in hypertension may be remodelling of the heart so that it entraps muscle fibres and increases their contractility.