Renal tubular function in horses during submaximal exercise.
Exercise-induced changes in renal function were examined during steady-state submaximal treadmill exercise in six unfit mares. Horses were randomly assigned to either an exercise or parallel control (no exercise) trial on day 1 and the alternate trial 1 wk later. The mares ran on a treadmill, set at a 6 degrees incline, for 1 h at 55-60% of maximal heart rate. Exercise significantly (P less than 0.05) increased plasma osmolality, plasma [K+], urine flow (+ 45%), Na+ excretion (+ 371%), K+ excretion (+ 57%), osmotic clearance (+ 32%), Na+ clearance (+ 391%), K+ clearance (+ 33%), and fractional Na+ excretion (+ 320%) and significantly decreased plasma [Cl-], Cl- excretion (-46%), Cl- clearance (-41%), and fractional Cl- excretion (-47%). Glomerular filtration rate, fractional K+ excretion, and free water clearance did not change during exercise. Atrial natriuretic peptide increased during exercise from 11 +/- 1 pg/ml at rest to a peak of 40 +/- 9 pg/ml (264%, P less than 0.05) at 40 min. Increases in plasma renin activity (66%, P less than 0.05) were accompanied by increases in plasma aldosterone concentration (760%, P less than 0.05). Vasopressin concentration increased (P less than 0.05) steadily over the 60-min period of exercise. It was concluded that, in horses, submaximal exercise-induced increases in urine flow and sodium excretion are associated with a concurrent increase in the plasma concentration of atrial natriuretic peptide.
McKeever
K H
KH
Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210.
Hinchcliff
K W
KW
Schmall
L M
LM
Muir
W W
WW
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000032:analysis / Q000652:urine; D001794:Blood Pressure; D003404:Creatinine / Q000097:blood; D004573:Electrolytes / Q000097:blood / Q000652:urine; D005260:Female; D006736:Horses / Q000502:physiology*; D007677:Kidney Function Tests; D007684:Kidney Tubules / Q000502:physiology*; D005082:Physical Exertion; D012083:Renin / Q000097:blood; D013997:Time Factors; D014556:Urine / Q000502:physiology
D004573:Electrolytes; D001127:Arginine Vasopressin; D009320:Atrial Natriuretic Factor; D003404:Creatinine; D012083:Renin