Effect of serum albumin on vascular smooth muscle metabolism.
In studies on metabolism of vascular smooth muscle, it was observed that incubation of intact porcine carotid artery strips with 3% bovine or porcine serum albumin had profound effects on the oxidation of substrates and O2 consumption. Arteries incubated over 180 min with charcoal-treated and dialyzed albumin demonstrated time-dependent stimulation of glucose oxidation (145%; P < 0.0001, n=6) and O2 consumption (116%; P< 0.001, n=6). These results were not mimicked by incubation with 3% solutions of ovalbumin or porcine skin gelatin. However, the oxidation of the medium chain fatty acid octanoate was inhibited in the presence of albumin over a broad range of octanoate concentrations (0.5-5.0 mM). Short chain fatty acid oxidation (acetate, 5 mM), in contrast, was not inhibited by albumin. Wash-out of albumin only partially reversed the stimulation of O2 consumption and incubation of arteries with a polyanionic compound, polyethylene sulfonate (5 mg/ml), blunted the stimulatory effect of albumin on O2 consumption. Albumin also produced anaplerosis of the Krebs cycle, and an increase in the content of glutamate and alanine (P < 0.005, n=8). The metabolic effects of albumin were associated with time-dependent uptake of albumin (30.9 +/- 1.5 nmol/g per 210 min; P<0.01, n=15). ATP-dependent proteolysis of the albumin taken up was also observed. These results demonstrate novel and important intracellular effects of serum albumin on energy metabolism of vascular smooth muscle.
Department of Medicine, and Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA. jbarron@rush.edu
J T
JT
Barron
L
L
Gu
E R
ER
Rodriguez
J E
JE
Parrillo
D000085:Acetates / Q000737:chemistry; D000818:Animals; D002210:Caprylates / Q000737:chemistry; D002339:Carotid Arteries; D002952:Citric Acid Cycle / Q000187:drug effects; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D018698:Glutamic Acid / Q000032:analysis; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010168:Palmitates / Q000737:chemistry; D012709:Serum Albumin / Q000378:metabolism* / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000378:metabolism / Q000494:pharmacology; D013552:Swine
D000085:Acetates; D002210:Caprylates; D010168:Palmitates; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D018698:Glutamic Acid; D005947:Glucose; C031492:octanoic acid