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Dopaminergic modulation of exercise hyperpnoea via D2 receptors in mice.
MedLine Citation:
PMID:  22041981     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Dopamine is related to behaviour (including arousal, motivation, and motor control of locomotion) and its turnover in the brain is increased during exercise. We examined the hypothesis that dopamine D2 receptors contribute to exercise hyperpnoea via central neural pathways using the D2-like receptor antagonist raclopride. We simultaneously measured ventilation and pulmonary gas exchange for the first time in mice. Mice injected with saline and raclopride (2 mg/kg body weight; i.p.) were compared for respiratory responses to constant-load exercise at 6 m/min. Each mouse was set in an airtight treadmill chamber. In the resting state, raclopride mice had reduced respiratory frequency (Rf) and minute ventilation (MV) decrease compared with saline mice, but PaCO2 and pulmonary gas exchange were not affected, showing that alveolar ventilation was maintained. Hyperoxic gas inhalation maintained MV in saline mice, and hypercapnic ventilatory responses between the two groups were similar. Treadmill exercise produced an abrupt increase in MV to a maximal level within 1 min and declined to a steady-state level in both groups. Raclopride mice had reduced Rf and MV compared with saline mice during steady states, but showed a similar increase in Rf and MV at exercise onset. Minute ventilation at the steady state was controlled along with VO2 increase in both groups, but was lowered in raclopride mice. Thus, D2 receptors participate in resting breathing patterns to raise Rf and exercise hyperpnoea in the steady state probably through behavioural control, and not central motor command, at exercise onset.
Authors:
Naoto Tsuchiya; Michiko Iwase; Masahiko Izumizaki; Ikuo Homma
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-31
Journal Detail:
Title:  Experimental physiology     Volume:  -     ISSN:  1469-445X     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-11-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Showa University.
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