Chronic recordings of cardiac contractility in conscious rats via telemetry

Abstract

Measurements of cardiac contractility in conscious freely moving animals are uncommon yet could offer considerable opportunity for understanding cardiovascular disease progression and treatment. We have utilized a new high‐fidelity solid‐state pressure sensor telemetry device for chronically measuring left ventricular pressure (LVP) and dP/dt in rats. The pressure sensor catheter tip (2‐Fr) was inserted into the left ventricular chamber through the apex of the heart and the telemeter body implanted in the abdomen. Data was measured up to 85 days after implant. The average daytime dP/dt max was 9706 ±264 mmHg/s, ranging from 8186 to 11382 mmHg/s (n=24). A circadian variation in dP/dt max and heart rate (HR) was observed with an average increase during the night phase in dP/dt max of 2198 ±280 mmHg/s and in HR of 60 ±5 bpm. The alpha‐adrenergic blocker propranolol, alpha‐adrenergic‐agonist isoproterenol, alpha1‐adrenergic agonist dobutamine, Ca2+ channel blocker verapamil and the calcium sensitizer levosimendan were administered repeatedly throughout the implant period, inducing changes in dP/dt max of −6000 to +13,000 mmHg/s from control and dose‐dependent time course changes in contractility. We propose that the chronic measurement of LVP in conscious rats can provide a valuable tool in cardiovascular research.