Contribution of carotid chemoreceptors to mesenteric venoconstriction during acute hypercapnia in rabbits.
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| Abstract |
The contribution of carotid chemoreceptors to hypercapnia-induced mesenteric venoconstriction was examined in 12 alpha-chloralose-anesthetized rabbits (1.0-1.6 kg). Surgical preparation consisted of a tracheotomy, femoral arterial and venous cannulation, and a midline laparotomy through which a 13-cm loop of ileum was exteriorized and superfused with physiological salt solution. Mesenteric vein diameter and intravenous pressure (using a servo-null measurement system) were measured in 500- to 1,000-micron mesenteric veins during 40-s periods of 15%, 20%, and 25% CO2 inhalation. Measurements were then repeated following bilateral ablation of the carotid chemoreceptors. Before denervation, mesenteric vein diameter constricted 6.5 +/- 1.1%, 11.9 +/- 1.1%, and 17.9 +/- 2.2% during the 15%, 20%, and 25% CO2 inhalation, respectively. After denervation, these values were reduced to 5.0 +/- 0.9%, 6.9 +/- 1.2%, and 8.4 +/- 1.3%, respectively. We conclude that activation of the carotid chemoreceptors by hypercapnia induces active mesenteric venoconstriction. After denervation of the carotid baroreceptors and chemoreceptors, there was also a small decrease in venule diameter proportional to the level of inspired CO2. We further conclude that noncarotid body chemoreceptor activation contributes to mesenteric venular constriction.
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| Authors | M Tominaga, T A Stekiel, Z J Bosnjak, J P Kampine |
| Journal | The American journal of physiology (Am J Physiol) Vol. 277 Issue 6 Pg. H2305-10 (12 1999) ISSN: 0002-9513 [Print] United States |
| PMID | 10600850 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.) |
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