Evaluation of pressor sentivity to norepinephrine infusion in dogs with iatrogenic hyperadrenocorticism
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...
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/33566 http://scholar.lib.vt.edu/theses/available/etd-06142002-161910/ |
| Summary: | 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. === Master of Science |
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