What is Aquaporin

This blog describes Aquaporin-water channels, types, locations, and more.

Table of content

Keywords: Aquaporins | Antidiuretic hormones | Channels |

Introduction:-

Aquaporins are integral cell membrane proteins that perform like channels for water and, in some cases, tiny solute molecules across the cell membrane.

Types and location:

In humans, about twelve aquaporins are detected. They are located in different types of cells. Their locations are :

Sr.no.	Type of Aquaporin	Cells and organs’ location
1.	AQ 0	Lens
2.	AQ 1	Blood vessels, eye, ear, and Proximal convoluted tubule
3.	AQ 2	Distal convoluted tubule, P-cells of collecting duct of the renal tubule.
4.	AQ 3	P-cells of collecting duct, Respiratory, urinary and digestive systems.
5.	AQ 4	Basolateral part of the plasma membrane of P-cells of collecting duct of the renal tubule.brain astrocytes, eye, ear, Skelton muscles, and parietal cells of the stomach.
6.	AQ 5	In the secretory cells of salivary, salivary, and sweat glands.They are also present in ears, and eyes.
7.	AQ 6	Intracellular vesicles in ‘I -cells’ of the renal tubule collecting duct.
8.	AQ 7	In brush borders of proximal convoluted tubular cells, kidneys, adipose tissues, and testis.
9.	AQ 8	In the proximal convoluted tubule, Intracellular in the liver, kidneys, and testis.
10.	AQ 9	In liver and leucocytes
11.	AQ 10	In the intestine.

Some aquaporins are also present in the bones, spleen, and lungs.

Aquaporins perform essential and specific functions in each organ.

Structure of aquaporins :

Aquaporins are protein molecules with a pore in the center.

Mechanism of functions:

The kidneys regulate pore size by the ‘Antidiuretic hormone. Under the influence of ADH size of pores increases leading to increased water absorption.https://amzn.to/3tEtIyO

Functions :

The primary function of Aquaporin is to provide channels for water absorption. Therefore, aquaporins are very important for water balance in humans. For example, mutations in aquaporin 2, present in P- cells of the collecting duct of the renal tubule, result in diabetes -insipidus.

Diabetes insipidus is characterized by increased output of diluted urine -about 20 liters or more in a day. Recall that the average urine output is only 1.2 -1.5 liters per day.

Diabetes insipidus is quite different from Diabetes mellitus. http://blog.totalphysiology.com/2021/01/diabetes-mellitus-you-must-know.html

Diabetes insipidus is due to a deficiency of ADH hormone, whereas Diabetes mellitus is due to insulin deficiency. In Diabetes mellitus, urine contains glucose, and its specific gravity is more than usual.

Aquaporin in the cell membrane. Aquaporin has a central pore through which water passes.ADH regulated the size of the pore.

Hashtags: Aquaporin#ADH#water balance# proximal convoluted tubule#