THE THICK ASCENDING LIMB OF HENLES LOOP - A KEY SEGMENT IN THE RENAL REGULATION OF ACIDO-BASIC STATUS

The thick ascending limb (TAL) of rat kidney has been shown to reabsor b bicarbonate and NH4+. Therefore, in vivo and in vitro studies have d emonstrated that bicarbonate absorption by the medullary TAL (mTAL) is influenced by peptide hormones (AVP, PTH), prostaglandin, osmolality and chronic metabolic acidosis. AVP, whose major effect is water balan ce regulation, also modulates acid-base handling in the mTAL, and then contribute to the regulation of renal acid excretion. These data sugg est that the TAL could play an important role in the physiology and pa thology of acid-base status.