C. Y. Hu

Antibodies to ovine adipocyte plasma membranes recognize tissue and species specific plasma membrane components

1. Ovine adipocyte plasma membrane (PM) contains three unique proteins that have relative molecular mass of 70, 106, and 110 kD which are lacking in PM from liver, kidney, heart, and red blood cells. 2. Two major proteins on ovine adipocyte PM having molecular mass of 44 and 46 kD which were also present on porcine adipocyte PM. 3. These ovine proteins could not be detected on either rat or chicken adipocyte PM.

Glycerolipid biosynthesis in adipose tissue of the bovine during growth

1. Rates of palmitate esterification in tissue slices and glycerophosphate acyltransferase activity in homogenates were determined in bovine subcutaneous and intermuscular adipose tissue at 340, 418 or 498 kg of live weight. 2. Lower rib section fat accretion rates were observed from 340 to 418 kg than from 418 to 498 kg. 3. Changes in palmitate esterification rates at different body weights were consistent with reduced rib section fat accretion as well as with reported differences in fat accretion in subcutaneous and intermuscular fat depots. 4. Glycerophosphate acyltransferase activity was increased at 418 kg and remained elevated whereas palmitate esterification was decreased at 418 and then increased at 498 kg. 5. Differences between palmitate esterification and glycerophosphate acyltransferase in vitro may have been related to differences in substrate supply.

Effect of catecholamines on lipolysis and esterification in vitro in adipose tissue of sheep fed low and high energy diets

Abstract The purpose of this study was to determine effects of the catecholamines clenbuterol, norepinephrine, and isoproterenol (10−5 m ), and dibutyryl-cyclic AMP (20 mmol/L on lipolysis and palmitate esterification in subcutaneous adipose tissue from sheep when fed a low energy diet, and then again when fed a high energy diet ad libitum. On the low energy diet, all catecholamines and cyclic AMP were lipolytic, and all inhibited palmitate esterification by 48% or more. When fed the high energy diet for 6 wk, only isoproterenol and cyclic AMP were lipolytic and inhibitory toward palmitate esterification, but less so than when sheep were fed the low energy diet. Blood plasma concentrations were not different for glucose, but free fatty acid greater and insulin concentrations lower for low energy-fed than for high energy-fed sheep. The mechanism for the altered catecholamine potency in ovine adipose tissue when sheep were fed the high energy diet is not clear; however, regulation of adrenergic receptors by changes in hormonal and/or metabolite balance because of diet were likely involved.

EFFECT OF INSULIN AND ADRENERGIC AGONISTS ON GLUCOSE TRANSPORT OF PORCINE ADIPOCYTES

1. Insulin increased basal 2-deoxyglucose uptake in isolated swine adipocytes by 75%. In the absence of insulin, isoproterenol did not inhibit basal 2-deoxyglucose transport. 2. Adenosine deaminase plus isoproterenol or theophylline alone reduced insulin effect by 10 and 40%, respectively. Isoproterenol alone or with 2-chloroadenosine did not inhibit insulin effect on glucose transport activity. 3. Insulin effect was inhibited by isoproterenol in the presence of theophylline but not in the presence of adenosine deaminase. 4. These results suggest that catecholamines do not counter-regulate basal and insulin-stimulated glucose transport in swine adipocytes.

Lipid metabolism of rat adipocytes in culture

Isolated differentiated rat adipocytes embedded in a collagen matrix were maintained in culture for 0, 4 and 14 days. Assessment of viability by either anabolic glucose metabolism or catabolic lipolytic metabolism can be misleading; both types of metabolism should be measured to establish the status of cells. Cells maintained morphological integrity even when not viable as judged by anabolic glucose metabolism.