Changes in regional vascular capacitance during prostacyclin-induced cardiac vagal reflex in pigs

Y. Wang, C. Drakonakis, J. L. Alderman, D. L. Rutlen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The purpose of this study was to determine the effects of the prostaglandin I2 (prostacyclin; PGI2)-induced cardiac vagal reflex on intestinal and liver blood volumes and the intestinal vascular pressure- volume (P-V) relationship. In anesthetized pigs, blood volumes were measured by blood-pool scintigraphy. Portal venous pressure was varied by graded inflation of a portal vein constrictor to determine the intestinal vascular P-V relationship. Proximal right coronary infusion of PGI2 at a rate of 0.15 μg · kg-1 · min-1 for 6 min increased intestinal blood volume by 7.0 ± 1.2% (P < 0.01, means ± SE) and shifted the intestinal vascular P-V relationship away from the pressure axis (i.e., a volume increase at a given venous pressure). This change was associated with decreases in liver blood volume and left ventricular end-diastolic pressure by 4.5 ± 1.2 (P < 0.01) and 17 ± 2% (P < 0.05), respectively. PGI2 also reduced central venous pressure by 16 ± 2% from 3.2 ± 0.5 mmHg (P < 0.05) and portal venous pressure by 7.0 ± 0.6% from 7.6 ± 0.6 mmHg (P < 0.05). These responses were abolished by bilateral vagotomy. The results demonstrate that intracoronary PGI2 infusion increases intestinal blood volume. This increase is mediated by a cardiac vagal reflex. The PGI2-induced shift in the intestinal vascular P-V relationship suggests that intestinal blood volume increases by an active change in vascular capacitance, whereas reductions in liver blood volume and left ventricular end-diastolic pressure appear to be due to passive mechanisms related to the shift of blood volume to the intestinal circulation.

Original languageEnglish (US)
Pages (from-to)H535-H539
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume267
Issue number2 36-2
DOIs
StatePublished - 1994
Externally publishedYes

Keywords

  • cardiac preload
  • intestinal and liver blood volume
  • pressure-volume relationship

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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