Resistance responses to local changes in plasma osmolality in three vascular beds.

GAZITGA, S., J. B. SCOTT, B. SWINDALL, AND F. J. HADDY. Resistance responses to local changes in plasma osmolality in three vascular beds. Am. J. Physiol. 220(Z) : 384-391. 1971 .-The effects of local changes in plasma osmolality (durations of 3-10 min) on resistance to blood flow were compared in the forelimb, renal, and coronary circulations of anesthetized dogs. A 40to 50mOsm/kg increase in plasma osmolality with sodium chloride, dextrose, or urea initially lowered resistance in all three beds. The responses to dextrose and sodium chloride waned in the forelimb and kidney but not in the heart. The response to urea waned in each bed. Renal resistance rose above control on stopping the infusion of each agent, but this response was only seen on stopping urea in the forelimb and heart. A 40to 50-mOsm/kg decrease in renal plasma osmolality caused a marked rise in renal resistance. Elevation of osmolality with dextrose or urea increased myocardial contractile force, whereas the same increase with sodium chloride caused an initial decrease in force followed by an increase. These studies show that the resistance response to osmolali ty depends to alter osmolality . not only on the bed but also on the agent used