Changes in hormonal excretion and urinary flow rate during CPPV and CPAP in healthy volunteers.

In healthy volunteers plasma antidiuretic hormone level, renin activity, and human growth hormone level remained unchanged during successive CPPV, CPAP, and control periods. The plasma level of insulin C-peptide was higher during CPPV than during the control period. Urine flow, glomerular filtration rate, free water clearance, and sodium excretion rate were lower during CPPV than during the successive CPAP and control periods. The renal function changes during CPPV may be a consequence of diminished cardiac output.