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RENAL PHYSIOLOGY

Renal HCO, Reabsorption

Factor	Principal Site of Action
Increased H^+ Secretion—Primary
4 HCOj" concentration (|> pH)	Entire nephror
f Arterial PC02	Entire nephror
Increased H’ Secretion—Secondary
f Rltered load of HCO3"	Proximal tubui
4 ECF volume	Proximal tubu--
f Angiotensin II	Proximal tubui-
f Aldosterone	Collecting duc-
Hypokalemia	Proximal tubu-
Decreased H^T Secretion—Primary
f HCO,' concentration { f pH)	Entire nephror
| Arterial PCO2	Entire nephro^r
Decreased H* Secretion—Secondary
| Filtered load of HCO3"	Proximal tubui-
^ ECF vołume	Proximal tubui-
4 Aldosterone	Collecting duc*
Hyperkalemia	Proximal tubui-

). Perkin-

Figurę 6.17 HCO.," Reabsorption -____

Bicarbonate is freely filtered and reabsorbed by thc proccss ot H*    balantc aft¹ the primary factors that regulate H secretion. Howet -

se<retion along the nephron. Normally, all the tiltered HCO,' is reab-    a number of other factors can also influence the kidne/s ability te

sorbed and nonę appears in the urine. Changes in systemie acid-base secrete H' and thus reabsorb I ICO,'