The effect of azaserine upon the proline and methyl alpha-D-glucoside transport systems of rat renal brush-border membranes
| Autor: | Betty Y.L. Hsu, Stanton Segal, Constance M. Marshall, Susan M. Corcoran |
|---|---|
| Rok vydání: | 1982 |
| Předmět: |
Male
Brush border Proline Stereochemistry Sodium Biophysics chemistry.chemical_element Biological Transport Active In Vitro Techniques Kidney Biochemistry chemistry.chemical_compound Glucoside Glucoside transport Proline transport medicine Animals Azaserine Methylglycosides Microvilli Vesicle Osmolar Concentration Methylglucosides Rats Inbred Strains Cell Biology Rats Kinetics chemistry medicine.drug |
| Zdroj: | Biochimica et biophysica acta. 692(1) |
| ISSN: | 0006-3002 |
| Popis: | An inhibitory effect of azaserine on Na+ dependent proline and methyl α- d -glucoside transport of the rat renal brush-border membrane vesicles has been demonstrated. The inhibitory effects of azaserine were not the results of the drug disrupting the membrane vesicles as shown in osmolarity studies, nor did it affect the transport systems' affinities for Na+. Azaserine acts as a non-competitive inhibitor for the proline transport system in renal brush- border membranes by lowering 37% and 27% in the V max 1 and V max 2 , respectively, when compared to that of control proline transport system. Azaserine had no effect upon the two K m values for proline uptake. Azaserine inhibition of methyl α- d -glucoside transport systems was characterized by a change in both K m 1 and V max 1 . Data indicate that methyl α- d -glucoside uptake by vesicles in the presence of 7.2 mM azaserine at 22°C resulted in 66% increase in K m 1 value and 44% decrease in V max 1 as compared to that of control vesicles. There was no detectable effect upon the K m 2 and V max 2 of the methyl α- d -glucoside transport system. No effect of the drug was observed when sodium was equilibrated across the membrane, indicating that azaserine altered the driving force exerted by a sodium gradient. Azaserine only slightly affected the relative contribution of the two K m slightly affected the relative contribution of the two K m systems to total proline uptake. Contrary to the observed effect of azaserine upon the proline transport system, azaserine exerted a distinct effect upon the relative contribution to total uptake by the two K m systems in the low methyl α- d -glucoside concentration range. In the presence of 7.2 mM azaserine, the low-affinity, high- K m transport system becomes the major contributor to total methyl α- d -glucoside uptake by isolated renal brush-border vesicles. |
| Databáze: | OpenAIRE |
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