Urinary prostaglandin and kallikrein excretion are not flow dependent in the rat

To study the relationship between urine flow, urinary prostaglandin (PG) and kallikrein excretion in the rat high urine flow was induced in hydropenic Long-Evans rats by either hypotonic volume expansion or with mannitol or with furosemide. PGE2 excretion remained unchanged during hypotonic volume expansion (134.5 +/- 29.7 before and 153.0 +/- 48.9 pg/min after) while it decreased significantly with mannitol (from 166.3 +/- 32.4 to 45.2 +/- 8.2 pg/min, p less than 0.01) and with furosemide (from 170.0 +/- 20.4 to 29.5 +/- 5.3 pg/min, p less than 0.001). PGF2 alpha excretion rates were slightly reduced following all three interventions. Urinary kallikrein excretion remained unchanged in all three groups of animals. It is concluded that, in contrast to humans and dogs in the rat urine flow and urinary PG excretion are not interlinked.