Neurohumoral regulation of the pulmonary circulation during circulatory hypotension in conscious dogs

W. P. Peterson, G. A. Trempy, K. Nishiwaki, D. P. Nyhan, P. A. Murray

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Abstract

We investigated the effects of circulatory hypotension (HYPO) on the left pulmonary vascular pressure-flow relationship in chronically instrumented conscious dogs and the role of five neurohumoral mechanisms in either mediating or modulating the response to this stimulus. HYPO was induced by acute (~15-min) inflation of a hydraulic occluder implanted around the thoracic inferior vena cava, which decreased systemic arterial pressure to ~55 mmHg. HYPO resulted in active pulmonary vasoconstriction (53-66%; P < 0.01) in intact conscious dogs. Sympathetic α1-adrenoreceptor block reduced (P < 0.01) the magnitude of HYPO-induced pulmonary vasoconstriction by 91- 99%. Neither sympathetic β-adrenoreceptor block nor cholinergic muscarinic receptor block had any significant effect on the magnitude of HYPO-induced pulmonary vasoconstriction. Surprisingly, angiotensin II receptor block increased (P < 0.05) HYPO-induced pulmonary vasoconstriction by 69-91%. In contrast, arginine vasopressin V1-receptor block reduced (P < 0.05) HYPO- induced pulmonary vasoconstriction by 34-41%. These results indicate that the pulmonary circulation of intact conscious dogs is actively regulated by three distinct neurohumoral mechanisms during HYPO. Sympathetic α1- adrenoreceptor activation is the primary mediator of HYPO-induced pulmonary vasoconstriction. Angiotensin II and arginine vasopressin exert opposing pulmonary vasodilator and vasoconstrictor effects during HYPO, whereas sympathetic β-adrenoreceptor and cholinergic muscarinic receptor activation do not appear to modulate the pulmonary vascular response to HYPO.

Original languageEnglish (US)
Pages (from-to)1675-1682
Number of pages8
JournalJournal of applied physiology
Volume75
Issue number4
DOIs
StatePublished - Jan 1 1993

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Keywords

  • angiotensin II
  • arginine vasopressin
  • autonomic nervous system
  • cholinergic muscarinic receptors
  • chronic instrumentation
  • hormones
  • pressure-flow plots
  • sympathetic α-adrenoreceptors
  • sympathetic β- adrenoreceptors

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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