In the present study we examined if adenosine acts directly on muscle afferents to stimulate muscle sympathetic nerve activity (MSNA). Six male subjects (25±2 yrs) had catheters inserted retrograde into the femoral artery and vein of one leg while peroneal nerve recordings were obtained from the contralateral leg. Bolus arterial injections of adenosine (2.5-9 mg) resulted in an elevation in the frequency (8±1 to 27±2 burst/min, P<0.05) and total amplitude (73±12 to 255 ±18 units, P<0.05) of MSNA with an onset latency of 16±1 sec post injection. When phenylephrine was infused intravenously prior to adenosine injection to prevent baroreceptor unloading, the increase in nerve frequency and amplitude was attenuated by 41 and 52%, respectively (P<0 05) with the onset latency being delayed to 19±2 sec. When adenosine was injected distal to a thigh cuff inflated to 220 mmHg, no increase in MSNA was observed until the cuff was deflated (34±2 burst/min and 276±28 units, P<0.05, onset latency 9±1 sec). The delayed onset latency in MSNA in conjunction with the effects of phenylephrine and cuff inflation strongly suggest that adenosine does not stimulate MSNA by direct activation of thin fiber muscle afferents.
|Original language||English (US)|
|State||Published - Dec 1 1997|
All Science Journal Classification (ASJC) codes
- Molecular Biology