Role of beta-adrenergic and cholinergic systems in acclimatization to hypoxia in the rat

R L Clancy, Y Moue, Lars Peter Erwig, P G Smith, N C Gonzalez

Research output: Contribution to journalArticle

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Abstract

The role of beta-adrenergic and muscarinic cholinergic systems on maximal treadmill exercise performance and systemic O2 transport during hypoxic exercise (PIO2 approximately 70 Torr) was studied in rats acclimatized to hypobaric hypoxia (PIO2 approximately 70 Torr for 3 weeks, A rats) and in non-acclimatized littermates (NA rats). Untreated A rats had lower resting (fH) and maximal heart rate (fHmax) and cardiac output (Q), and higher maximal O2 uptake (VO2max) than NA. The only effect of cholinergic receptor blockade with atropine (Atp) was an increase in pre-exercise fH to comparable levels in A and in NA. beta 1-adrenergic receptor blockade with atenolol (Aten) lowered pre-exercise fH and (fHmax) to comparable values in A and in NA rats. However, since both pre-exercise fH and fHmax were lower in untreated A, the effect of Aten was relatively smaller in A. Aten reduced maximal exercise cardiac output (Qmax) in NA; however, tissue O2 extraction increased such that VO2max was not affected. Aten did not influence Qmax or any other parameter of systemic O2 transport in A. In conclusion the increased cholinergic tone may be responsible for the lower resting fH but not the lower fHmax of A; the integrity of the beta-adrenergic system is not necessary to attain VO2max in hypoxia either in A or in NA; the decreased response to beta-adrenergic stimulation in A limits the efficacy of this system on the mechanisms of systemic O2 transport and reduces the effect of its blockade on these mechanisms.
Original languageEnglish
Pages (from-to)75-84
Number of pages10
JournalRespiration Physiology
Volume107
Issue number1
DOIs
Publication statusPublished - 1 Jan 1997

Fingerprint

Atenolol
Acclimatization
Adrenergic Agents
Cholinergic Agents
Adrenergic beta-1 Receptors
High Cardiac Output
Cholinergic Receptors
Atropine
Cardiac Output
Heart Rate
Hypoxia

Keywords

  • Acclimatization
  • Animals
  • Anoxia
  • Blood Gas Analysis
  • Hemodynamics
  • Hyperventilation
  • Male
  • Oxygen Consumption
  • Physical Exertion
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Adrenergic, beta
  • Receptors, Muscarinic
  • Acclimatization, hypoxia
  • Exercise, maximal, hypoxia, adrenergic, cholinergic systems
  • Hypoxia, acclimatized
  • Mammals, rats

Cite this

Role of beta-adrenergic and cholinergic systems in acclimatization to hypoxia in the rat. / Clancy, R L; Moue, Y; Erwig, Lars Peter; Smith, P G; Gonzalez, N C.

In: Respiration Physiology, Vol. 107, No. 1, 01.01.1997, p. 75-84.

Research output: Contribution to journalArticle

Clancy, R L ; Moue, Y ; Erwig, Lars Peter ; Smith, P G ; Gonzalez, N C. / Role of beta-adrenergic and cholinergic systems in acclimatization to hypoxia in the rat. In: Respiration Physiology. 1997 ; Vol. 107, No. 1. pp. 75-84.
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T1 - Role of beta-adrenergic and cholinergic systems in acclimatization to hypoxia in the rat

AU - Clancy, R L

AU - Moue, Y

AU - Erwig, Lars Peter

AU - Smith, P G

AU - Gonzalez, N C

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N2 - The role of beta-adrenergic and muscarinic cholinergic systems on maximal treadmill exercise performance and systemic O2 transport during hypoxic exercise (PIO2 approximately 70 Torr) was studied in rats acclimatized to hypobaric hypoxia (PIO2 approximately 70 Torr for 3 weeks, A rats) and in non-acclimatized littermates (NA rats). Untreated A rats had lower resting (fH) and maximal heart rate (fHmax) and cardiac output (Q), and higher maximal O2 uptake (VO2max) than NA. The only effect of cholinergic receptor blockade with atropine (Atp) was an increase in pre-exercise fH to comparable levels in A and in NA. beta 1-adrenergic receptor blockade with atenolol (Aten) lowered pre-exercise fH and (fHmax) to comparable values in A and in NA rats. However, since both pre-exercise fH and fHmax were lower in untreated A, the effect of Aten was relatively smaller in A. Aten reduced maximal exercise cardiac output (Qmax) in NA; however, tissue O2 extraction increased such that VO2max was not affected. Aten did not influence Qmax or any other parameter of systemic O2 transport in A. In conclusion the increased cholinergic tone may be responsible for the lower resting fH but not the lower fHmax of A; the integrity of the beta-adrenergic system is not necessary to attain VO2max in hypoxia either in A or in NA; the decreased response to beta-adrenergic stimulation in A limits the efficacy of this system on the mechanisms of systemic O2 transport and reduces the effect of its blockade on these mechanisms.

AB - The role of beta-adrenergic and muscarinic cholinergic systems on maximal treadmill exercise performance and systemic O2 transport during hypoxic exercise (PIO2 approximately 70 Torr) was studied in rats acclimatized to hypobaric hypoxia (PIO2 approximately 70 Torr for 3 weeks, A rats) and in non-acclimatized littermates (NA rats). Untreated A rats had lower resting (fH) and maximal heart rate (fHmax) and cardiac output (Q), and higher maximal O2 uptake (VO2max) than NA. The only effect of cholinergic receptor blockade with atropine (Atp) was an increase in pre-exercise fH to comparable levels in A and in NA. beta 1-adrenergic receptor blockade with atenolol (Aten) lowered pre-exercise fH and (fHmax) to comparable values in A and in NA rats. However, since both pre-exercise fH and fHmax were lower in untreated A, the effect of Aten was relatively smaller in A. Aten reduced maximal exercise cardiac output (Qmax) in NA; however, tissue O2 extraction increased such that VO2max was not affected. Aten did not influence Qmax or any other parameter of systemic O2 transport in A. In conclusion the increased cholinergic tone may be responsible for the lower resting fH but not the lower fHmax of A; the integrity of the beta-adrenergic system is not necessary to attain VO2max in hypoxia either in A or in NA; the decreased response to beta-adrenergic stimulation in A limits the efficacy of this system on the mechanisms of systemic O2 transport and reduces the effect of its blockade on these mechanisms.

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KW - Animals

KW - Anoxia

KW - Blood Gas Analysis

KW - Hemodynamics

KW - Hyperventilation

KW - Male

KW - Oxygen Consumption

KW - Physical Exertion

KW - Rats

KW - Rats, Sprague-Dawley

KW - Receptors, Adrenergic, beta

KW - Receptors, Muscarinic

KW - Acclimatization, hypoxia

KW - Exercise, maximal, hypoxia, adrenergic, cholinergic systems

KW - Hypoxia, acclimatized

KW - Mammals, rats

U2 - 10.1016/S0034-5687(96)02502-9

DO - 10.1016/S0034-5687(96)02502-9

M3 - Article

VL - 107

SP - 75

EP - 84

JO - Respiration Physiology

JF - Respiration Physiology

SN - 0034-5687

IS - 1

ER -