Journal article
Mechanism of decreased baroreceptor activity in chronic hypertensive rabbits. Role of endogenous prostanoids
The Journal of clinical investigation, Vol.86(2), pp.625-630
08/1990
DOI: 10.1172/JCI114754
PMCID: PMC296770
PMID: 2117025
Abstract
We examined the contribution of endogenous prostanoids to baroreceptor activation in chronic renal hypertension. Baroreceptor activity was recorded from the vascularly isolated carotid sinus during slow ramp increases in pressure in rabbits anesthetized with pentothal and chloralose. Mean arterial pressure averaged 133 +/- 4 mmHg in hypertensive rabbits (one kidney, one wrap, n = 12) and 85 +/- 3 mmHg in normotensive rabbits (one kidney, no wrap, n = 13). Baroreceptor activity was decreased significantly (P less than 0.05) in the hypertensive compared with the normotensive rabbits. The decreased baroreceptor activity could not be explained by decreased distensibility of the carotid sinus (sonomicrometers). Inhibition of the endogenous formation of prostanoids with intrasinus administration of indomethacin (50 microM) decreased baroreceptor activity in normotensive (P less than 0.05) but not in hypertensive rabbits over a wide range of pressures. At a pressure of 120 mmHg, activity declined from 61 +/- 14 spikes/s before indomethacin to 47 +/- 12 spikes/s with indomethacin, i.e., a drop of 24 +/- 4%. In contrast, corresponding values in hypertensive rabbits averaged 41 +/- 13 and 40 +/- 12 spikes/s (-1 +/- 2%). Intrasinus prostacyclin, on the other hand, increased activity in both groups: at 120 mmHg activity increased from 62 +/- 9 to 92 +/- 15 spikes/s (51 +/- 17%) in normotensive rabbits and from 29+/- 7 to 47 +/- 14 spikes/s (68 +/- 23%) in hypertensive rabbits. Neither indomethacin nor prostacyclin (n = 5) influenced the pressure-diameter relation of the carotid sinus. The increase in prostacyclin (6-keto-PGF 1 alpha) formation by the sinus in response to its exposure to arachidonic acid (10 microM) was significant (P less than 0.05) in the normotensives (1,627 +/- 344%; n = 5) but not in the hypertensives (583 +/- 353%; n = 5). We conclude that the decreased baroreceptor activity in chronic hypertension may not be caused by decreased distensibility of the vascular wall of the sinus and that endogenous prostanoids that contribute to baroreceptor activation in normotensive rabbits fail to do so in hypertensive rabbits. This appears to be due to decreased formation of prostacyclin rather than decreased sensitivity of the baroreceptors to prostacyclin. The results suggest a new mechanism that contributes to chronic baroreceptor resetting in hypertension.
Details
- Title: Subtitle
- Mechanism of decreased baroreceptor activity in chronic hypertensive rabbits. Role of endogenous prostanoids
- Creators
- Peili Xie - Cardiovascular Center, University of Iowa, College of Medicine, Iowa City 52242Mark W Chapleau - Cardiovascular Center, University of Iowa, College of Medicine, Iowa City 52242Thomas S McDowell - Cardiovascular Center, University of Iowa, College of Medicine, Iowa City 52242George Hajduczok - Cardiovascular Center, University of Iowa, College of Medicine, Iowa City 52242Francois M Abboud - Cardiovascular Center, University of Iowa, College of Medicine, Iowa City 52242
- Resource Type
- Journal article
- Publication Details
- The Journal of clinical investigation, Vol.86(2), pp.625-630
- DOI
- 10.1172/JCI114754
- PMID
- 2117025
- PMCID
- PMC296770
- ISSN
- 0021-9738
- eISSN
- 1558-8238
- Language
- English
- Date published
- 08/1990
- Academic Unit
- Molecular Physiology and Biophysics; Internal Medicine
- Record Identifier
- 9984025341902771
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