Amino acid and glucose transport in sarcolemmal vesicles from chick embryo heart

Abstract

Purified plasma membranes from chick embryo heart are shown to retain several functional properties of intact cardiac cells. 1. (1) Muscarinic cholinergic receptors copurify with previously used cell-surface markers, i.e., (K +-dependent) p- nitrophenylphosphatase and insulin receptors (Paris, S., Fosset, M., Samuel, D. and Ailhaud, G. (1977) J. Mol. Cell. Cardiol. 9, 161–174). 2. (2) Neutral amino acids ( l-alanine and α-aminoisobutyric acid) are actively transported into these osmotically active vesicles when an Na + electrochemical gradient is imposed. The affinity and specificity for amino acids are similar to those described for intact cardiac cells. 3. (3) d-Glucose is taken up more rapidly than l-glucose. The stereospecific transport system is saturable and Na +-independent. The K m value is close to that observed in intact cells with glucose analogues.