Capillary and muscle fiber type changes in DOCA‐salt hypertensive rats

• Published in: The Anatomical record Vol. 246; no. 2; pp. 208 - 216
• Main Authors: Hernández, Noelina, Torres, Sonia H., Finol, Héctor J., Sosa, Amparo, Cierco, Maria
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.10.1996
• Subjects: Adenosine Triphosphatases - metabolism; Animals; Capillaries - pathology; Desoxycorticosterone; histochemistry; Hypertension - chemically induced; Hypertension - enzymology; Hypertension - pathology; Microscopy, Electron; muscle capillaries; muscle fiber types; Muscle Fibers, Skeletal - classification; Muscle Fibers, Skeletal - enzymology; Muscle Fibers, Skeletal - pathology; Muscle, Skeletal - blood supply; Muscle, Skeletal - enzymology; Muscle, Skeletal - pathology; pericytes; Rats; Rats, Sprague-Dawley; smooth muscle cells; Sodium Chloride; Time Factors; transmission electron microscopy
• ISSN: 0003-276X; 1097-0185
• DOI: 10.1002/(SICI)1097-0185(199610)246:2<208::AID-AR7>3.0.CO;2-X

Background Discrepancies concerning the effect of hypertension on capillaries and muscle fiber types in skeletal muscle have been reported. This study demonstrates the effects of hypertension produced by deoxicorticosterone acetate (DOCA) and salt load on the extensor digitorum longus (EDL) and soleus muscles of the rat. Methods Hypertension was produced by subcutaneous injections of DOCA and supplemented with drinking 1% NaCl solution. One group was treated for 7 weeks and another for 14 weeks. Fiber types were classified by ATPase reaction at pH 4.35, capillaries were counted in α‐amylase‐PAS‐stained sections, and ultrastructure was studied by conventional methods of transmission electron microscopy. Results In the 7‐week group, a decrease in the percentage of IIA, with an increase in IIB and I fiber types, was found in the EDL muscle. Capillary density was not reduced, but endothelial cells showed surface infoldings into the lumen. Altered mitochondria and an infiltrate of macrophages was present in pericytes. In the 14‐week group, a decrease in capillary to fiber index was found in both soleus and EDL muscles. EDL fiber type changes were the same as at 7 weeks. The soleus muscle showed an increased percentage of type I fibers. Some capillaries were degenerated, and others showed an increase in the endothelial cell area covered with pericytes, which resembled smooth muscle cells. Conclusion Hypertensive rats showed changes in the percentage of fiber types in the soleus and EDL muscles. Capillaries adjacent to muscle fibers were reduced and showed morphological changes that resembled arterioles. © 1996 Wiley‐Liss, Inc.