This proposal is designed to investigatethe mechanism of the release of AVP and ACTH and plasma renin activity in response to hemorrhage. The proposal addresses the relative contribution of atrial cardiac receptors and arterial baroreceptor in these responses as well as their interactions. The investigator found that blocking cardiac receptors with local anesthetics injected into the pericardial space of conscious dogs had no effect on vasopressin release whereas vasopressin release during hemorrhage was more tightly correlated to the decrease in arterial blood pressure. Based on these results he suggested that the atrial receptors are not involved in the release of AVP in hemorrhage or, at least, they are not the dominant influence; thereby challenging traditional concepts concerning the release of AVP. The investigator has devised techniques to expand these studies. These techniques make use of unanesthetized dog preparations in which the aortic baroreceptors as well as one carotid sinus are denervated, while the other carotid sinus can be isolated from the circulation by means of occluding devises and its pressure can be maintained constant. In addition, by means of occluding devises on the thoracic inferior vena cava, venous return can be regulated thereby controlling atrial pressure. Finally, the cardiac receptors can be eliminated by the injection of local anesthetics into the pericardial space. Using this preparation the relative contribution from the cardiac and arterial baroreceptors in the control of AVP, plasma renin and ACTH can be addressed. In addition, the interactions between these receptors can be evaluated.
The specific aims of the proposal are: 1) to show that unloading cardiac receptors alone stimulates an increase in plasma renin activity but not an increase in AVP and ACTH in response to thoracic inferior vena cava occlusion; 2) To show that unloading arterial baroreceptor alone can stimulate increases in plasma AVP and ACTH similar to those obtained during systemic hypotension but that the plasma renin activity response is greater when both arterial and atrial receptors are unloaded; and, 3) to show that afferent signals from the heart chronically inhibit renin but not AVP and ACTH secretion in conscious normovolemic dogs.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL041313-07
Application #
2445172
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1988-07-01
Project End
1999-06-30
Budget Start
1997-07-01
Budget End
1998-06-30
Support Year
7
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Surgery
Type
Schools of Medicine
DUNS #
003255213
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Thrasher, Terry N (2002) Unloading arterial baroreceptors causes neurogenic hypertension. Am J Physiol Regul Integr Comp Physiol 282:R1044-53
Thrasher, T N; Shifflett, C (2001) Effect of carotid or aortic baroreceptor denervation on arterial pressure during hemorrhage in conscious dogs. Am J Physiol Regul Integr Comp Physiol 280:R1642-9
Thrasher, T N; Chen, H G; Keil, L C (2000) Arterial baroreceptors control plasma vasopressin responses to graded hypotension in conscious dogs. Am J Physiol Regul Integr Comp Physiol 278:R469-75
Thrasher, T N; Keil, L C (2000) Systolic pressure predicts plasma vasopressin responses to hemorrhage and vena caval constriction in dogs. Am J Physiol Regul Integr Comp Physiol 279:R1035-42
Thrasher, T N; Keil, L C (1998) Arterial baroreceptors control blood pressure and vasopressin responses to hemorrhage in conscious dogs. Am J Physiol 275:R1843-57
Andersen, J L; Andersen, L J; Thrasher, T N et al. (1994) Left heart and arterial baroreceptors interact in control of plasma vasopressin, renin, and cortisol in awake dogs. Am J Physiol 266:R879-88
O'Donnell, C P; Thompson, C J; Keil, L C et al. (1994) Renin and vasopressin responses to graded reductions in atrial pressure in conscious dogs. Am J Physiol 266:R714-21
Thrasher, T N (1994) Baroreceptor regulation of vasopressin and renin secretion: low-pressure versus high-pressure receptors. Front Neuroendocrinol 15:157-96
Thrasher, T N; Ramsay, D J (1993) Interactions between vasopressin and atrial natriuretic peptides. Ann N Y Acad Sci 689:426-37
O'Donnell, C P; Keil, L C; Thrasher, T N (1993) Vasopressin, renin, and cortisol responses to hemorrhage during acute blockade of cardiac nerves in conscious dogs. Am J Physiol 265:R220-9

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