MEASUREMENT OF BLOOD-PRESSURE AND HEART-RATE BY TELEMETRY IN CONSCIOUS, UNRESTRAINED MARMOSETS

A system is described for the continuous measurement of blood pressure, heart rate, and motor activity by telemetry in conscious marmosets freely moving in their home cages. Consistent diurnal variations in these parameters were observed under standard conditions, although these parameters were sensitive to changes in the environment. Blood pressure values were similar to those measured by nontelemetric methods in conscious, restrained marmosets. However, heart rate was lower, indicating that telemetry is less stressful. The suitability of this system for assessing the effects of blood pressure-lowering drugs was evaluated. An acute or a prolonged treatment with a converting enzyme inhibitor of marmosets maintained on a low-sodium diet induced a fall in blood pressure as previously observed using nontelemetric methods. With telemetry, however, more accurate information on the duration of response and the effects of the treatment on the diurnal rhythms was obtained. These observations demonstrate the advantages of telemetry for evaluating the hemodynamic effects of drug treatments under physiological conditions.