Abstract
The uptake of α-aminoisobutyric (AIB) by guinea pig taenia coli was linear with time over a 5-h period. There was a saturable component with D(m) of 0.7 mM and a maximal value of 4.75 mmol/kg tissue per hour. A second nonsaturable component of uptake became important at high concentrations of AIB (>5 mM). Preincubation in K+-free or Na+-free (high-K+) media greatly reduced uptake. The dependence of AIB uptake on outside [Na+]([Na+]o) was approximately linear over the range 0-140 mM. With [Na+]o equal to 25 mM the uptakes with various substitutes were in the order sucrose > Mg2+ > choline+ > Li+ > Cs+ > Rb+ = K+. Addition of ouabain or removal of K+ during efflux of AIB led to marked increases in the efflux rate, ouabain being the more effective treatment. Changes in tissue Na+ and K+ levels were found to be slightly greater with ouabain than with K+-free medium. Lanthanum (5 nM) prevented the uptake of Na+ seen in K+-free medium also abolished the increase in the rate of loss of AIB. It also reduced the rise in tissue Na+ produced by ouabain; there was a corresponding reduction in the ouabain-induced increase in the rate of loss of AIB. It is concluded that both the influx and efflux AIB in this tissue are Na+ dependent, and that the accumulation of AIB relies on the transmembrane Na+ gradient.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1114-1121 |
| Number of pages | 8 |
| Journal | Canadian Journal of Physiology and Pharmacology |
| Volume | 57 |
| Issue number | 10 |
| State | Published - 1979 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Physiology
- Pharmacology
Cite this
The uptake and efflux of α-aminoisobutyric acid by the smooth muscle of the guinea pig's taenia coli. / Widdicombe, Jonathan; Paton, D. M.
In: Canadian Journal of Physiology and Pharmacology, Vol. 57, No. 10, 1979, p. 1114-1121.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The uptake and efflux of α-aminoisobutyric acid by the smooth muscle of the guinea pig's taenia coli
AU - Widdicombe, Jonathan
AU - Paton, D. M.
PY - 1979
Y1 - 1979
N2 - The uptake of α-aminoisobutyric (AIB) by guinea pig taenia coli was linear with time over a 5-h period. There was a saturable component with D(m) of 0.7 mM and a maximal value of 4.75 mmol/kg tissue per hour. A second nonsaturable component of uptake became important at high concentrations of AIB (>5 mM). Preincubation in K+-free or Na+-free (high-K+) media greatly reduced uptake. The dependence of AIB uptake on outside [Na+]([Na+]o) was approximately linear over the range 0-140 mM. With [Na+]o equal to 25 mM the uptakes with various substitutes were in the order sucrose > Mg2+ > choline+ > Li+ > Cs+ > Rb+ = K+. Addition of ouabain or removal of K+ during efflux of AIB led to marked increases in the efflux rate, ouabain being the more effective treatment. Changes in tissue Na+ and K+ levels were found to be slightly greater with ouabain than with K+-free medium. Lanthanum (5 nM) prevented the uptake of Na+ seen in K+-free medium also abolished the increase in the rate of loss of AIB. It also reduced the rise in tissue Na+ produced by ouabain; there was a corresponding reduction in the ouabain-induced increase in the rate of loss of AIB. It is concluded that both the influx and efflux AIB in this tissue are Na+ dependent, and that the accumulation of AIB relies on the transmembrane Na+ gradient.
AB - The uptake of α-aminoisobutyric (AIB) by guinea pig taenia coli was linear with time over a 5-h period. There was a saturable component with D(m) of 0.7 mM and a maximal value of 4.75 mmol/kg tissue per hour. A second nonsaturable component of uptake became important at high concentrations of AIB (>5 mM). Preincubation in K+-free or Na+-free (high-K+) media greatly reduced uptake. The dependence of AIB uptake on outside [Na+]([Na+]o) was approximately linear over the range 0-140 mM. With [Na+]o equal to 25 mM the uptakes with various substitutes were in the order sucrose > Mg2+ > choline+ > Li+ > Cs+ > Rb+ = K+. Addition of ouabain or removal of K+ during efflux of AIB led to marked increases in the efflux rate, ouabain being the more effective treatment. Changes in tissue Na+ and K+ levels were found to be slightly greater with ouabain than with K+-free medium. Lanthanum (5 nM) prevented the uptake of Na+ seen in K+-free medium also abolished the increase in the rate of loss of AIB. It also reduced the rise in tissue Na+ produced by ouabain; there was a corresponding reduction in the ouabain-induced increase in the rate of loss of AIB. It is concluded that both the influx and efflux AIB in this tissue are Na+ dependent, and that the accumulation of AIB relies on the transmembrane Na+ gradient.
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M3 - Article
VL - 57
SP - 1114
EP - 1121
JO - Canadian Journal of Physiology and Pharmacology
JF - Canadian Journal of Physiology and Pharmacology
SN - 0008-4212
IS - 10
ER -