Transport mechanisms for renal tubular excretion of creatinine in the chicken

Abstract

Renal clearance of creatinine was previously, known to exceed inulin clearance in many species and the creatinine -to-inulin clearance ratio was reduced by probenecid, indicating an organic acid transport pathway. The present studies demonstrated the tubular excretion of creatinine by the Sperber technique of unilateral renal portal infusion. This tubular transport was inhibited by either organic acid or organic base competitors, indicating transport by two systems simultaneously. The amphoteric nature of creatinine may be one factor in allowing this dual transport process, which has previously been demonstrated for the zwitterion norepinephrine.