[Renal responses to left atrial stretch in the cat]

The effects of left atrial stretch (LAS) on urine volume (UV), urinary sodium excretion (UNaV) and potassium excretion (UKV) were studied in 50 anesthetized cats. LAS resulted in a marked increase in UV, UNaV and UKV (all P less than 0.001) in the intact animals. Although LAS still caused an increase in UV and UNaV (P less than 0.01) after vagotomy, the increments were significantly less than those in vagi intact animals (P less than 0.005). LAS also induced an increase in UV, UNaV and UKV (P less than 0.05) in the vagi intact cats with heparin infusion (10U/min/kg), but the increments were significantly less than those in the cats without heparin (P less than 0.05). The responses to LAS were abolished by infusion of heparin after vagotomy (P greater than 0.05). Following left renal denervation, the responses to LAS remained unchanged in the innervated kidney, while those in denervated kidney were attenuated, though still significant. The difference in the response between the innervated and the denervated kidneys was statistically significant (P less than 0.05). These results indicate that LAS can induce a marked increase in UV, UNaV and UKV in anesthetized cats through both neural and humoral mechanisms.