Red cell in cardiac muscle is richly Connective endowed with mitochondria transverse bule Gap junction (sarcosomes)which contain the Manduria respiratory enzymes necessary H zone for oxidative phosphorylation. To provide adequate o2 and substrate for its metabolic machinery, the myocardium is also endowed with a rich capillary supply, about one capillary per fiber.• cardiac muscle is richly endowed with mitochondria (sarcosomes) which contain the respiratory enzymes necessary for oxidative phosphorylation. • To provide adequate O2 and substrate for its metabolic machinery, the myocardium is also endowed with a rich capillary supply, about one capillary per fiber