Catecholamine regulation of local lactate production in vivo in skeletal muscle and adipose tissue: role of -adrenoreceptor subtypes.
BACKGROUND
The regulation of lactate production in skeletal muscle (SM) and adipose tissue (AT) is not fully elucidated.


OBJECTIVE
Our objective was to investigate the catecholamine-mediated regulation of lactate production and blood flow in SM and AT in healthy, normal-weight subjects by using microdialysis.


METHODS
First, lactate levels in SM and AT were measured during an iv norepinephrine infusion (n = 11). Local blood flow was determined with the 133Xe-clearance technique. Second, muscle lactate was measured during hypoglycemia and endogenous epinephrine stimulation (n = 12). Third, SM was perfused with selective beta(1-3)-adrenoreceptor agonists in situ (n = 8). Local blood flow was measured with the ethanol perfusion technique.


RESULTS
In response to iv norepinephrine, the fractional release of lactate (difference between tissue and arterial lactate) increased by 40% in SM (P = 0.001), whereas remaining unchanged in AT. Blood flow decreased by 40% in SM (P < 0.005) and increased by 50% in AT (P < 0.05). In response to hypoglycemia, epinephrine increased 10-fold, and the fractional release of lactate in SM doubled (P < 0.0001). The blood flow remained unchanged. The beta2-agonist, terbutaline, caused a marked concentration-dependent increase of muscle lactate and blood flow (P < 0.0001). The beta(1)-agonist, dobutamine, induced a discrete increase of muscle lactate (P < 0.0001), and the blood flow remained unchanged. The beta3-agonist, CPG 12177, did not affect muscle lactate or blood flow.


CONCLUSIONS
Catecholamines stimulate lactate production in SM, but not in AT. In SM, the beta2-adrenoreceptor is the most important beta-adrenergic receptor subtype in the regulation of lactate production.
Qvisth
Veronica
V
Department of Medicine, Karolinska University Hospital-Huddinge, Karolinska Institutet, SE-141 86 Stockholm, Sweden. veronica.qvisth@ki.se
Hagström-Toft
Eva
E
Enoksson
Staffan
S
Bolinder
Jan
J
D000273:Adipose Tissue / Q000098:blood supply / Q000378:metabolism*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004280:Dobutamine / Q000494:pharmacology; D004837:Epinephrine / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism; D007773:Lactates / Q000097:blood / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D013726:Terbutaline / Q000494:pharmacology
D000318:Adrenergic beta-Agonists; D001786:Blood Glucose; D007773:Lactates; D011943:Receptors, Adrenergic, beta; D004280:Dobutamine; D013726:Terbutaline; D004837:Epinephrine