The Journal of Physiological Sciences
Online ISSN : 1880-6562
Print ISSN : 1880-6546
ISSN-L : 1880-6546
Regular Papers
Ultrastructural Findings for the Mitochondrial Subpopulation of Mice Skeletal Muscle after Adrenergic Stimulation by Clenbuterol
Santosh SundalSushma Sharma
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2007 Volume 57 Issue 1 Pages 7-14

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Abstract

Clenbuterol, a β-adrenoceptor agonist, has been reported to induce skeletal muscle hypertrophy. However, it has also been known to reduce aerobic exercise performance and to deleteriously affect endurance and sprint exercise performance in rats. In the present study, the chronic administration of clenbuterol (2 mg/kg body weight; 30 days) resulted in various ultrastructural changes in three different types of muscles, gastrocnemius, a mixed-fiber type; anterior latissimus dorsi (ALD), a predominantly fast-twitch type; and diaphragm, a largely oxidative-type. The most prominent changes included mitochondrial swelling, matricular vesiculation in mitochondria, mitochondrial hyperplasia, sarcoplasmic vesiculation, and intermyofibrillar dilations. An increase in the cross-sectional area of both the subsarcolemmal (170, 167, and 79%) and the intermyofibrillar (129, 134, and 84%) mitochondria is noticed in the gastrocnemius, ALD, and diaphragm, respectively. The ultramicroscopic and morphometric results suggest drug-induced defects in contractile and oxidative activities.

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© 2007 by The Physiological Society of Japan
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