Type of Document	Master's Thesis
Author	Martinez, Nivia Ivellise
URN	etd-06142002-161910
Title	Evaluation of pressor sentivity to norepinephrine infusion in dogs with iatrogenic hyperadrenocorticism
Degree	Master of Science
Department	Veterinary Medical Sciences
Advisory Committee	Advisor Name Title Panciera, David L. Committee Chair Abbott, Jonathan A. Committee Member Leib, Michael S. Committee Member Monroe, William Edward Committee Member Wilcke, Jeffrey R. Committee Member
Keywords	norepinephrine hypertension canine iatrogenic hyperadrenocorticism
Date of Defense	2002-04-15
Availability	unrestricted
Abstract Evaluation of pressor sensitivity to norepinephrine infusion in dogs with iatrogenic hyperadrenocorticism Nivia I. Martínez (ABSTRACT) Objective: To evaluate pressor sensitivity to catecholamines in dogs after induction of iatrogenic hyperadrenocorticism (I-HAC) by serial arterial blood pressure measurements during infusions of increasing dose rates of norepinephrine. Animals: Eight dogs with I-HAC induced by administration of oral hydrocortisone at a mean dose of 3.3 mg/kg PO TID for 42-49 days and 8 control dogs which received empty gelatin capsules PO TID for 42-49 days. Procedure: Systolic, diastolic, mean blood pressure and heart rate measurements were recorded after sequential administration of increasing dose rates of norepinephrine (0.1, 0.125, 0.2, 0.3, 0.4, 0.6 and 0.8 mg/kg/min) for 10 minutes. The changes in systolic, diastolic, mean blood pressure and heart rate were compared between control dogs and dogs with I-HAC. Results: Dogs in the I-HAC group had a more pronounced pressor response to norepinephrine infusions than control dogs. The infusions were not completed in 7 of the 8 dogs in the I-HAC group versus 3 dogs in the control group due to severe elevations in systolic blood pressure. The mean change in systolic blood pressure was consistently higher in dogs in the I-HAC group. The difference was statistically significant at the 0.2 mg/kg/min norepinephrine dose rate. The mean change in heart rate was consistently lower in the I-HAC group, a difference that was significant at the 0.2 mg/kg/min norepinephrine dose rate. Conclusions and clinical relevance: Increased pressor sensitivity or decreased baroreceptor response to norepinephrine was seen in dogs with I-HAC suggesting that this mechanism is involved in the development of hypertension in canine hyperadrenocorticism.
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