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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3-4
pubmed:dateCreated
1976-3-1
pubmed:abstractText
Using the stop flow microperfusion technique with simultaneous capillary perfusion the secretory rate of H+ ions in the proximal tubule was evaluated by measuring the level flow reabsorption as well as the static head concentration difference of 3H labeled glycodiazine. At ambient glycodiazine concentration of 21 mmol/l the level flow reabsorption is in the same range as that of bicarbonate. In the early proximal loops the reabsorption is 20% greater than in the late proximal loops. The carbonic anhydrase inhibitors acetazolamide and 3,4-methylene-dioxyphenyl-sulfonamide (both 10(-4) M) as well as furosemide (10 (-3) M) inhibit the glycodiazine reabsorption 43%, 27% and 22% respectively. Thiocyanate (2-10(-2) M), however, exerted only an insignificant inhibition (12%). When Na+ in the ambient perfusion solutions was replaced by Li+ or choline+ the glycodiazine transport was strongly reduced. Ouabain (5-10(-2) M) inhibited too, but amiloride (10(-3) M) had no effect on glycodiazine transport. The glycodiazine transport was 28% reduced in metabolic alkalosis and to a smaller although significant extent (17%) in metabolic acidosis; it was unchanged in chronic hypercapnia. In chronic K+ depletion the glycodiazine reabsorption was accelerated by 12% only in the early proximal loops. Chronic parathyroidectomy as well as acute substitution with parathyroid hormone had no effect on the glycodiazine absorption. The main conclusions are: Proximal H+ transport proceeds with suitable buffers. Although independent of HCO3- and carbonic anhydrase, it could be partially inhibited by CA inhibitors. H+ transport is supposed to proceed as countertransport with Na+ ions. In chronic alkalosis the H+ transport is reduced.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0031-6768
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
357
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
149-63
pubmed:dateRevised
2009-10-27
pubmed:meshHeading
pubmed:year
1975
pubmed:articleTitle
Renal proximal tubular buffer-(glycodiazine) transport. Inhomogeneity of local transport rate, dependence on sodium, effect of inhibitors and chronic adaptation.
pubmed:publicationType
Journal Article