Oubain is a specific inhibitor of the active transport of sodium ions out of the

Question

Oubain is a specific inhibitor of the active transport of sodium ions out of the cell and is therefore a valuable tool in the studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by oubain ? Exaplain your answer in each case a) Facilitated diffusion of glucose into a muscle cell b) Active transport of dietary phenylalanine (an amino acic) across the intestinal mucosa (the epithelial els that point into the lumen of your intestine). c) Uptake of potassium by red blood cells d) Active uptake of lactose by the bacteria that colonize your intestine

Explanation / Answer

Q) 1) Oubain is a specific inhibitor of active transport of sodium ions out of the cell and is therefore a valuable tool in the studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by oubain?

Answer:-

B - Active transport of phenylalanine (an amino acid) across the intestinal mucosa (the epithelial cell that point into your intestine).

C- Uptake of potassium by Red blood cells.

Explanation-

Case -A - Facilitated diffusion of glucose into a muscle cell.

This is not sensitive to inhibition by oubain because sodium ion co-transport is required for indirect active transport of glucose (by Na+ / Glucose symporter) symporter is an integral membrane protein, which helps in the transport of many types of molecules across the cell membrane. They are associated with secondary active transport, but not with facilitated diffusion of glucose into muscle cells, because it takes place by glucose uniports (uniports are the integral membrane proteins which helps in facilitated diffusion).

Case-B

Active transport of dietary phenylalanine across the intestinal mucosa.

Explanation:- Yes it does affect this process in body, because the amino acids are usually transported into cell along with transport of Na+ ions by indirect active transport, and here the dietary phenylalanine is an amino acid, and it is transported into cell along with Na+ ions, and this can take place if Na+ gradient is regenerated by Na+ / K+ pump. As Oubain is a sodium inhibitor, it affects the process.

Case-C :- Uptake of potassium by Red blood cells.

Explanation:- yes this process is also sensitive to inhibition by oubain. Because during uptake of potassium by red blood cells Na+ / K+ anti-porter is used (anti-porters are a type of integral membrane protein which helps in secondary active transport of two or more different molecules or ions across a phospholipid plasma membrane in opposite direction, here the inward pumping of potassium ion is correlated with outward pumping of sodium ions). So when Oubain inhibits active transport of Sodium ions the process gets affected.

Case-D:- Active uptake of lactose by the bacteria that colonizes your intestine.

Explanation- This process is not affected in body , because active transport of sugar and amino acids in bacteria takes place by the proton gradients, they are not linked with sodium co-transport as in case of animal cells. Here in this case uptake of glucose, which is a sugar by bacteria remaining in our intestine takes place by the proton gradient. So it is not sensitive to inhibition by Oubain.

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