Respiratory effects of pressor and depressor agents in conscious rats.

Journal Article (Journal Article)

We hypothesized that the respiratory baroreflex in conscious rats is either more transient, or has a higher pressure threshold than in other species. To characterize the effect of arterial pressure changes on respiration in conscious rats, ventilation (V) was measured by the plethysmographic technique during injections, or infusions, of pressor and depressor agents. Bolus injections of angiotensin II (Ang II) or arginine vasopressin (AVP), transiently increased mean arterial pressure (MAP; mean +/- SE) 43+/-6 and 28+/-5 mm Hg (1 mm Hg = 133.3 Pa), respectively, and immediately reduced tidal volume (Vt) and, in the case of AVP, V. In contrast, by 10 min of a sustained elevation of MAP (40+/-3 mm Hg) with infusion of Ang II, Vt, f, and V were not different from control levels. Bolus injection of sodium nitroprusside (SNP) to lower MAP (-28+/-3 mm Hg) immediately increased breathing frequency (f) and V, whereas sustained infusion of SNP to lower MAP (-21+/-3 mm Hg) did not change for V at 10 and 20 min. In conscious rats, both injection and infusion of the pressor agent PE (+40 to 50 mm Hg) stimulated f and V; this contrasted with anesthetized rats where PE inhibited f and V, as reported by others. In conscious rats, respiratory responses associated with baroreflexes adapt rapidly and, in the case of PE, can be overridden by some other mechanism.

Full Text

Duke Authors

Cited Authors

  • Walker, JK; Jennings, DB

Published Date

  • July 1998

Published In

Volume / Issue

  • 76 / 7-8

Start / End Page

  • 707 - 714

PubMed ID

  • 10030450

Electronic International Standard Serial Number (EISSN)

  • 1205-7541

International Standard Serial Number (ISSN)

  • 0008-4212

Digital Object Identifier (DOI)

  • 10.1139/cjpp-76-7-8-707


  • eng