Adenosine transport in rat liver plasma membrane vesicles
R H Moseley1, S Jarose, P Permoad
1Department of Internal Medicine, Veterans Affairs Medical Center, Ann Arbor, Michigan.
The American Journal of Physiology
|November 1, 1991
Summary
This study reveals that sodium-dependent nucleoside transport is selectively located on the bile canalicular membrane in rat livers. This mechanism likely reclaims adenosine produced from ATP degradation within bile canaliculi.
Area of Science:
- Hepatology
- Membrane Transport
- Biochemistry
Background:
- Liver plasma membrane ecto-ATPase activity is concentrated on the bile canalicular membrane.
- ATP degradation within bile canaliculi releases adenosine.
Purpose of the Study:
- To investigate the presence and characteristics of nucleoside transport on canalicular and basolateral liver plasma membranes.
- To determine if adenosine is reclaimed by a specific transport system on the canalicular membrane.
Main Methods:
- Utilized rat liver plasma membrane vesicles (canalicular and basolateral).
- Assessed [3H]adenosine uptake under varying sodium gradients and membrane potentials.
- Tested effects of nucleoside analogs and inhibitors.
Main Results:
- Sodium gradient significantly stimulated [3H]adenosine uptake in canalicular vesicles, unlike basolateral vesicles.
- Uptake was dependent on Na+ and membrane potential, and inhibited by gramicidin D.
- Canalicular adenosine transport showed saturability (Km = 8.3 µM) and was unaffected by a specific nucleoside transport inhibitor.
Conclusions:
- Demonstrates asymmetric distribution of hepatic Na+-dependent nucleoside transport.
- Suggests this transport system selectively reclaims adenosine on the bile canalicular membrane.
- This reclamation process is linked to ecto-ATPase activity.
More Related Videos
16:26Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport
Published on: June 28, 2014
13:16Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Related Concept Videos
01:31ABC Transporters: Exporter
ATP-binding cassette or ABC transporter is the largest superfamily of integral membrane proteins. The transporters have transmembrane-binding domains (TMDs) and nucleotide-binding domains (NBDs). The TMDs are specific to their substrates, whereas the NBDs are similar to engines that complete ATP hydrolysis to complete the substrate transport. They can be full transporters consisting of two TMDs and NBDs, half transporters with one TMD and NBD, while some encoded with a single TMD or NBD are...
01:42The ADP/ATP Carrier Protein
ADP/ATP carrier or AAC protein is the most abundant carrier protein in the inner mitochondrial membrane. It transports large quantities of ADP and ATP, equivalent to the average human body weight, every day. Among other transporters, ACC protein is one of the best-studied members of the mitochondrial carrier protein family. The ADP/ATP carrier protein comprises two transmembrane helices connected to a loop and a single alpha-helix on the matrix side. It switches between two conformational...
01:30ATP Driven Pumps III: V-type Pumps
V-type pumps are ATP-driven pumps found in the vacuolar membranes of plants, yeast, endosomal and lysosomal membranes of animal cells, plasma membranes of a few specialized eukaryotic cells, and some prokaryotes. They are also known as the V1Vo-ATPase, that couple ATP hydrolysis to transport protons against a concentration gradient.
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
01:17Pore Transport and Ion-Pair Transport
Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
01:14Active Transport
Active transport is a critical biological process that allows cells to move solutes against an electrochemical gradient. This process requires direct energy input and is characterized by its selectivity, saturability, and susceptibility to competitive inhibition.
Primary active transporters, like Na+, K+ and -ATPase, directly utilize ATP to move ions across the membrane. These transporters play significant roles in various physiological processes. For instance, Na+, K+ and -ATPase maintain...
Primary active transporters, like Na+, K+ and -ATPase, directly utilize ATP to move ions across the membrane. These transporters play significant roles in various physiological processes. For instance, Na+, K+ and -ATPase maintain...
01:07Physiological Pharmacokinetic Models: Incorporating Hepatic Transporter-Mediated Clearance
Drug transporters are critical in drug absorption, distribution, and excretion processes. They should be included in physiological-based pharmacokinetic (PBPK) models, which help predict human drug disposition. However, predicting this is challenging during drug development, especially when liver transport is involved. However, with a realistic representation of body transport processes, an accurate model may be possible.
A recent model describes pravastatin's hepatobiliary excretion, mediated...
A recent model describes pravastatin's hepatobiliary excretion, mediated...