Reflex stimulation of renal sympathetic nerve activity and blood pressure in response to apnea

C. P. O'Donnell, A. R. Schwartz, P. L. Smith, J. L. Robotham, R. S. Fitzgerald, M. Shirahata

Research output: Contribution to journalArticlepeer-review

Abstract

The purpose of this study was to examine the role of afferent input in the reflex modulation of renal sympathetic nerve activity (SNA) in response to apnea. Apneas of 20-, 40-, and 60-s duration were induced in the anesthetized, paralyzed cat (n = 7) ventilated with either room air or 100% oxygen. While receiving room air, there were increases (p < 0.005) in renal SNA of 34.5 ± 4.2%, 53.3 ± 6.4%, and 59.9 ± 7.2% of maximum during the 20-, 40-, and 60-s apneas, respectively. There were corresponding increases (p < 0.025) in mean arterial pressure (P̄ā) of 9 ± 3, 30 ± 9, and 45 ± 12 mm Hg during the 20-, 40-, and 60-s apneas while receiving room air, respectively. The effect of 100% oxygen was to reduce (p < 0.0001) the renal SNA response to apnea, at a matched level of Pa(CO2), by at least 800%, and to eliminate any increase in P̄ā. During the first breath of the postapneic period, there was a partial inhibition of renal SNA. During the second and third breaths of the postapneic period, there was a marked fall in renal SNA that was associated with a precipitous decline in directly recorded carotid chemoreceptor activity (n = 2). The magnitude of the fall in renal SNA after apnea was related to the degree of postapneic hypertension. We conclude that hypoxic chemoreceptor stimulation is the predominant factor generating the renal SNA response to apnea, with modulating inputs from thoracic afferents and arterial baroreceptors likely contributing to the marked inhibition of renal SNA immediately after the apnea.

Original languageEnglish (US)
Pages (from-to)1763-1770
Number of pages8
JournalAmerican journal of respiratory and critical care medicine
Volume154
Issue number6
DOIs
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine

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