Evaluation of blood flow parameters in addition to blood pressure and electrocardiogram in the conscious telemetered beagle dog

Abstract

Introduction The objective of this study was to evaluate a model for measuring blood flow parameters in addition to blood pressure, heart rate and electrocardiogram (ECG) in conscious telemetered restrained and unrestrained beagle dogs. Methods Male beagle dogs were instrumented with fully implantable ITS radio telemetry devices for the measurement of blood pressure and ECG. In addition, the dogs were instrumented with a probe around the pulmonary artery for the measurement of blood flow by ultrasound. Dobutamine at 5, 10 and 20 μg/kg/min, given intravenously to sling restrained animals ( n = 4), and minoxidil at 2 mg/kg, given orally to unrestrained animals ( n = 4), were selected as test compounds known to cause changes in the cardiovascular parameters of interest in this work. Results Dobutamine produced a small increase in mean (9%) and systolic blood pressure (5%), and an increase in pulse pressure (37%) and heart rate (30%). The additional blood flow parameters showed that dobutamine also increased stroke volume (21%) and cardiac output (58%) and reduced total peripheral resistance (52%). Minoxidil treatment resulted in a prolonged reduction in mean, systolic and diastolic blood pressure (up to 24%). Additionally, a prolonged increase in heart rate (169%) and cardiac output (120%) were observed along with a reduction in total peripheral resistance (62%). The effects of both compounds were consistent with their known pharmacology. Discussion The results show that measurement of blood flow parameters can be successfully added to the standard telemetered cardiovascular dog model to provide valuable additional information on the effects of compounds on the cardiovascular system.