In:
Journal of Applied Physiology, American Physiological Society, Vol. 102, No. 1 ( 2007-01), p. 350-357
Abstract:
The aim of this study was to investigate whether GABA A and/or GABA B receptor-mediated mechanisms contribute to the impaired ventilatory response and reduced maximal aerobic exercise capacity in obese Zucker rats. Ten lean and 10 obese Zucker rats were studied at 12 wk of age. Minute ventilation (V̇e), tidal volume (Vt), and breathing frequency (f) during room air breathing and in response to 10 min of hypercapnia (8% CO 2 ) and 30 min of hypoxia (10% O 2 ) were measured by the barometric method, and peak oxygen consumption (V̇o 2 peak ) was measured by an enclosed metabolic treadmill following the randomized blinded subcutaneous administration of equal volumes of DMSO (vehicle), bicuculline (selective GABA A receptor antagonist, 1 mg/kg), and phaclofen (selective GABA B receptor antagonist, 1 mg/kg). Administration of bicuculline and phaclofen to lean animals had no effect on V̇e and V̇o 2 peak . Similarly, phaclofen failed to alter V̇e and V̇o 2 peak in obese rats, although it did significantly increase f after 5–20 min of hypoxia. In contrast, bicuculline increased V̇e and Vt relative to DMSO during room air breathing and after 10–30 min of hypoxic exposure in obese rats, but it did not increase V̇e at 5 min of hypoxemia. Bicuculline increased V̇o 2 peak relative to DMSO in obese Zucker rats. We conclude that endogenous GABA acting on GABA A receptors can modulate V̇e and V̇o 2 peak in obese but not in lean Zucker rats, whereas endogenous GABA acting on GABA B receptors modulates f during hypoxia (5–20 min) in obese rats in a very different manner from that when acting on GABA A receptors.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/japplphysiol.01463.2005
Language:
English
Publisher:
American Physiological Society
Publication Date:
2007
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
