Gadolinium attenuates renal sympathetic activity in cats

The exercise pressor reflex, which arises from contracting skeletal muscle, activates the sympathetic nervous system during exercise. Although metaboreceptors in contracting muscle are well known to play an important role in evoking the exercise pressor reflex, the role played by mechanoreceptors is less certain. Therefore, we investigated whether the blockade of mechanoreceptors with gadolinium (10 mM; 1ml) attenuated the responses of renal sympathetic efferents to both calcaneal tendon stretch and static contraction of the triceps surae muscles. We examined the renal sympathetic nerve responses to both maneuvers before and after injecting gadolinium into the popliteal artery in twelve chloralose‐urethane‐anesthetized cats. The pressor responses (Δ 25±3 vs. Δ17±2 mmHg) and the increases in renal sympathetic activity (Δ443±131 vs. Δ253±117 au) to tendon stretch were significantly attenuated by gadolinium. Likewise, the pressor responses (Δ 23±4 vs. Δ13±1 mmHg) and the increases in renal sympathetic activity (Δ332±118 vs. Δ158±56 au) to static contraction were significantly attenuated by gadolinium. Thus, mechanical stimuli arising in contracting skeletal muscle play a role in activating the sympathetic outflow to the kidney. Supported by NIH HL30710