Stress can enhance the renin response to reduced renal perfusion pressure

It was recently reported that electrical stimulation of the hypothalamus could enhance the renin response to reductions in renal perfusion pressure. However, electrical stimulation of brain sites may activate neural pathways that never function physiologically. In the present investigation an external stress in the form of a jet of air to the face was applied to achieve a more physiological activation of the sympathetic nervous system. Conscious restrained rats, instrumented with pneumatic occluding cuffs around the aorta proximal to the renal arteries, were used to determine the relationship between renal perfusion pressure (RPP) and plasma renin activity (PRA) in the control state and in the presence of the stress. The jet of air produced a rightward shift in the relationship between RPP and PRA and also increased the slope, suggesting an enhanced sensitivity. Both the rightward shift and the increase in slope were absent in animals with bilateral renal denervation. In animals with adrenal enucleation, the rightward shift was still present but there was no significant increase in the sensitivity. These data suggest that an external activation of the central nervous system (by a stress) has the potential to modulate the responsiveness of the kidney to nonneural stimuli for renin secretion.