Studies on isoproterenol-induced cardiomegaly in rats

摘要: Abstract 1. Isoproterenol (ISO) (5 mg. per kilogram, subcutaneously) induced maximal increases in the wet and dry weights of four chambers rat heart when administered twice daily for 10 days. The degree cardiomegaly was related to duration ISO treatment but not greater, most instances, after 20 80 kilogram than 5 kilogram. size regressed discontinued. Propranolol antagonized response. 2. by accompanied microscopic evidence infarctlike cardiac necrosis. severity damage, although quantitated, appeared increase with dosage or treatment. 3. Total extracellular water, Na+, Ca++, Cl− increased relation dose. Heart K+ 1 decreased 2 Mg++ same extent all doses. 4. levels protein, RNA, DNA were augmented RNA increasing more DNA. incorporation C14-labelled amino acids into protein heart, skeletal muscle, enhanced ISO. 5. Catecholamine contents (microgram gram) heart) as 6. kilogram) elicited prolonged tachycardia hypotension unanesthetized rats prepared chronic, aortic catheters.