Telemetric Recording of Renal and Carotid Blood Flow Velocity and Arterial Blood Pressure Simultaneously in Rats

Abstract

Hypertension‐induced barotrauma without or with concomitant vasoconstriction, tissue ischemia and hypoxia has been postulated to initiate and drive the pathogenic cascades that lead to hypertension induced tissue injury. Yet the precise temporal relationship between arterial pressure and tissue blood flow over time as causative mechanisms for barotrauma remain unresolved and controversial. A major technical limitation has been the absence of methods allowing simultaneous high fidelity long‐term measurement of blood flow and arterial pressure in conscious animals. Transonic has developed a cutting edge technology to continuously evaluate arterial blood pressure and two blood flow velocity's simultaneously in conscious rats. Here, we report the first demonstration of recording renal and carotid blood flow and arterial pressure using this new multi‐variable telemetric system. A solid state pressure sensor was placed in the abdominal aorta and 0.8mm and 0.5mm in diameter flow probes were sutured on the renal and carotid artery, respectively, in Wistar rats. Both flow velocity signals correlated with the arterial pressure signal and exhibited constant lag times. After 5 min of carbogen breathing carotid vascular resistance decreased by 31±4% while renal vascular resistance decreased by 7±1%. These experiments demonstrate the feasibility of the technique for high fidelity temporal profiling of both blood pressure and blood flows to renal and carotid vascular beds simultaneously in conscious rats. British Heart Foundation funded research.