Journal of Lipid Research, Vol. 9, 453-459, July 1968
Copyright © 1968 by Lipid Research, Inc.

Uptake and esterification of palmitate by rat diaphragm in vitro

Gustav Schonfeld

Physiology Branch, USAF School of Aerospace Medicine, Brooks Air Force Base, Texas 78235

The contribution of exogenously supplied palmitate to the intracellular palmitate pool and its role in esterification were studied for the intact rat diaphragm in vitro. Palmitate-1-¹⁴C attached to albumin in various molar ratios () was taken up by the tissue in an initial rapid phase which led, after 4 min, to a steady-state level of tissue free fatty acid. The level was determined by but also by the albumin concentration below 2 g/100 ml. The exogenous palmitate taken up constitutes one-quarter to three-quarters of the intracellular palmitate pool as is increased from 0.5 to 5.5 (albumin concentration 2 g/100 ml).

Turnover rates of intracellular palmitate at a given are stable over 35 min of incubation, as indicated by constant rates of esterification (largely to triglyceride, but also to phospholipids) and by the unchanging specific activity ratios between intracellular and medium palmitate-1-¹⁴C. These ratios also indicate that only a portion of the palmitate taken up is available for exchange with the albumin complex in the medium.

Calculation of esterification rates at various values suggests that not all of the palmitate is in a pool that is available for esterification.

Supplementary key words free fatty acid • muscle lipid metabolism • palmitate • fatty acid: albumin molar ratio

Submitted on December 8, 1967
Accepted on March 12, 1968

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