QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Verney, E. Articles by Sidransky, H. Search for Related Content PubMed PubMed Citation Articles by Verney, E. Articles by Sidransky, H.

Alterations in Cardiac Protein Metabolism in Rats Force-fed a Threonine-devoid Diet^{1 ,2}

Department of Pathology, University of South Florida, College of Medicine, Tampa, Florida 33620

Hearts of young rats force-fed for 3 days a purified diet devoid of threonine (an experimental kwashiorkor-like model) were investigated and compared with those of control animals force-fed a complete diet. The hearts of the experimental animals revealed an increase in weight (9% in wet weight and 14% in dry weight), a 11% increase in protein, a 124% increase in glycogen, a 13% increase in lipid, a 29% increase in RNA and a 3% increase in DNA. In vivo ¹⁴C-leucine incorporation into cardiac proteins for 1 hour revealed a 60% increase in specific activity and a 64% increase in total incorporation. Increases in specific activity were present in cardiac proteins of mitochondria, supernatant, myofibrillar and actomyosin fractions of the experimental animals in comparison to the control animals. Size distribution of cardiac polyribosomes revealed a shift toward heavier aggregation with a decrease in lighter units in the hearts of the experimental animals. In vitro ¹⁴C-leucine incorporation into proteins revealed increased incorporation when using cardiac microsomes of the experimental animals in comparison to those of the control animals. When animals were force-fed the threonine-devoid diet for 3 days and then were force-fed the complete diet for 1 day, in vivo ¹⁴C-leucine incorporation into cardiac proteins revealed a decreased stimulation (from 69% to 24%) indicating reversibility of the effect. A rapid, nutritionally induced model of enhanced cardiac protein synthesis and of cardiac hypertrophy is described in young rats force-fed a threonine-devoid diet.

KEY WORDS: • cardiac protein synthesis • in vivo and in vitro • cardiac polyribosomes • cardiac hypertrophy

¹ Supported by U. S. Public Health Service Research Grants AM-05908 and AM-16530 from the National Institute of Arthritis and Metabolic Diseases.

² A preliminary report was presented at the Meeting of the Federation for Experimental Biology in Atlantic City, N. J., April 1972; Federation Proc. 31, 731 (abstr.).

Manuscript received 25 September 1973.