Plasma angiotensin II changes with noise exposure at three levels of ambient temperature

Significant plasma elevations of the powerful vasoconstrictor angiotensin II (AII) were measured in rats following exposure to either 100-dB or 20-dB SPL white noise in three environmental temperatures (5 degrees 21 degrees, and 38 degrees C). Loud noise exposure in the normal temperature condition (21 degrees C) and both temperature extremes with soft noise exposure resulted in plasma AII elevations. The two extreme temperatures combined with loud noise exposure resulted in plasma AII concentrations not different from the levels observed following 20-dB noise at normal temperature. These results indicate that separately administered noise and temperature extremes stimulate the production of AII and thus vasoconstriction. Simultaneous exposure to multiple stressors including noise and temperature extremes may result in severely elevated plasma catecholamines and reduce renal responsiveness to beta-adrenergic stimulation thus reducing plasma AII levels.