Long‐term recording of sympathetic nerve activity in conscious rats using telemetry

Abstract

Increased sympathetic nerve activity (SNA) is believed to contribute to the development of cardiovascular disease. Since short‐term recordings can't predict long‐term changes in SNA, longer recordings are required. Our study describes a high resolution (8 kHz) telemetry system (www.telemetryresearch.com) that allows chronic recording of SNA in conscious rats. We instrumented rats with renal SNA transmitters and femoral cannulas and repeatedly recorded SNA and arterial pressure (AP) responses to acute cold water stress, to pharmacological stress with cocaine, to baroreceptor stimuli (phenylephrine and nitroprusside), and to ganglionic blockade with trimethaphan to assess background activity. A patented inductive power transfer technique allowed the transmitter to recharge while in the conscious animal. Responses to stressors included reproducible changes in renal SNA corresponding to AP. After 2 weeks, SNA was recorded in most rats studied (75%). Signal to noise ratio, assessed with trimethaphan (10 mg/kg), did not change significantly over the course of two weeks (day 2 SNA decreased 41±5%, day 14 decreased 30±4%). This study demonstrates the ability to record renal SNA for at least two weeks in conscious rats using telemetry. We suggest this technique could provide novel insight into the role of SNA in the development of cardiovascular disease. Supported by USPHS DA13256.