Db. Jennings, THE PHYSICOCHEMISTRY OF [H- ROLES OF PCO2, STRONG IONS, AND THEIR HORMONAL REGULATORS(] AND RESPIRATORY CONTROL ), Canadian journal of physiology and pharmacology, 72(12), 1994, pp. 1499-1512
I describe how the dietary intake of strong ions potentially affects t
he regulation of ventilation and the Pco(2) of body fluids in two ways
. First, changing the dietary intake of NaCl can alter the concentrati
on difference between strong cations and strong anions (the [SID] of S
tewart) of body fluids. Experimental observations indicate that the [S
ID] in brain fluids or cerebrospinal fluid ([SID](CSF)) could be the s
timulus to central chemoreceptors. [SID](CSF) consistently predicts ve
ntilatory regulation of Pco(2), whereas [H+](CSF) does not. Pco(2) act
s as a stimulus to ventilation independently of [SID](CSF) and possibl
y at higher as well as lower centers of the nervous system. I relate t
he concept of [SID] regulation of arterial Pco(2) to the alphastat hyp
othesis of protein function, respiratory control, and [H+] homeostasis
. Second, altering the dietary intake of NaCl changes the levels of ho
rmones involved in salt and water balance. Angiotensin II acts central
ly to stimulate ventilation. Evidence for the roles of both the renal
and brain renin-angiotensin systems in respiratory control, and the mo
dulation of respiratory control by vasopressin are reviewed. These pep
tide systems probably act via circumventricular organs of the brain to
affect respiratory control and (or) by changing strong ion concentrat
ions in brain fluids. Questions to be resolved on the role of [SID](CS
F) and hormones in respiratory adaptations, and experiments required t
o improve our understanding of the control of ventilation, are address
ed in the concluding comments.