In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 287, No. 4 ( 2004-10), p. R742-R748
Abstract:
We examined the role of efferent neural signaling in regulation of net hepatic glucose uptake (NHGU) in two groups of conscious dogs with hollow perfusable coils around their vagus nerves, using tracer and arteriovenous difference techniques. Somatostatin, intraportal insulin and glucagon at fourfold basal and basal rates, and intraportal glucose at 3.8 mg·kg −1 ·min −1 were infused continuously. From 0 to 90 min [ period 1 ( P1)], the coils were perfused with a 37°C solution. During period 2 [ P2; 90–150 min in group 1 ( n = 3); 90–180 min in group 2 ( n = 6)] , the coils were perfused with −15°C solution to eliminate vagal signaling, and the coils were subsequently perfused with 37°C solution during period 3 ( P3). In addition, group 2 received an intraportal infusion of norepinephrine at 16 ng·kg −1 ·min −1 during P2. The effectiveness of vagal suppression was demonstrated by the increase in heart rate during P2 (111 ± 17, 167 ± 16, and 105 ± 13 beats/min in group 1 and 71 ± 6, 200 ± 11, and 76 ± 6 beats/min in group 2 during P1–P3, respectively) and by prolapse of the third eyelid during P2. Arterial plasma glucose, insulin, and glucagon concentrations; hepatic blood flow; and hepatic glucose load did not change significantly during P1–P3. NHGU during P1-P3 was 2.7 ± 0.4, 4.1 ± 0.6, and 4.0 ± 1.2 mg·kg −1 ·min −1 in group 1 and 5.0 ± 0.9, 5.6 ± 0.7, and 6.1 ± 0.9 mg·kg −1 ·min −1 in group 2 (not significant among periods). Interruption of vagal signaling with or without intraportal infusion of norepinephrine to augment sympathetic tone did not suppress NHGU during portal glucose delivery, suggesting the portal signal stimulates NHGU independently of vagal efferent flow.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.00041.2004
Language:
English
Publisher:
American Physiological Society
Publication Date:
2004
detail.hit.zdb_id:
1477297-8
SSG:
12
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