Before discussing the effects of cholesterol on membrane fluidity, we first need to know what is cholesterol and membrane fluidity.
Cholesterol is a thick wax-like substance which is not bad for your health. To be honest, your body needs cholesterol to build cells; however, too much cholesterol will be problematic for your health.
Effects Of Cholesterol On Membrane Fluidity
The production of cholesterol originates from two sources. Your liver is responsible for making all the cholesterol your body needs.
The excessive amount of cholesterol in your body comes from food, which is derived from animals. For example, meat, poultry, and full-fat dairy products are some of the high cholesterol that contains food; this type of food is called dietary cholesterol.
Some tropical oils, like palm oil, palm kernel oil, and coconut oil, which are often found in baked goods, can also contribute to the catalysis of your body’s cholesterol levels.
These types of food also contain high levels of saturation and trans fat. That extra fat causes your liver to produce more cholesterol than usual. In simple language, the growth in cholesterol levels means switching from a healthy body to an unhealthy one.
Now you know what cholesterol is, let us dive deeper into understanding how high cholesterol levels in the body is risky.
How cholesterol affects the health of the body
Cholesterol circulates in your blood; as the level of cholesterol increases, so does the risk of your health. This is why you need to keep a check on your cholesterol levels as frequently as possible.
There are two types of cholesterol: LDL cholesterol, which is terrible for your health, and HDL, which is essential for your health. Therefore, you should know that too much LDL cholesterol or too low HDL levels will increase the risk for your body.
This will slowly lead to the build-up of cholesterol in the arteries’ inner walls that feed the brain and heart. Cholesterol can also join the other substance to form a thick deposit on the side of the arteries.
This will narrow the arteries and make them less flexible; this condition is termed as atherosclerosis.
If, for instance, a blood clot is formed, blocking one of these narrowed arteries could cause a stroke or and heart attack. High cholesterol levels are one of the crucial controllable risk factors for coronary heart disease, Heart attack, and stroke.
The chance of risk can increase if you smoke, have high blood or diabetes. The viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane is known as membrane fluidity.
The packing of lipids influences the fluidity of the membrane. The membrane fluidity is also affected by fatty acids; the unsaturated or saturated nature of fatty acids affects the membrane fluids.
Saturated fatty acids do not have double bonds in the hydrocarbon chain, decreasing the fluidity making the membrane very strong and stacked tightly. Simultaneously, the unsaturated fatty acids have at least one double bond, which makes the membrane very fluidic.
The membrane fluidity is also affected by cholesterol, making the cell membrane fluidic and rigid in nature.
The membrane fluidity is contributed by the mosaic nature of the membrane, its phospholipid chemistry, and cholesterol.
Cholesterol plays the bidirectional regulator’s role because it helps stabilize the membrane and raises its temperature at high temperatures.
The intercalation between the phospholipids and preventing them from clumping together and stiffening is caused when at a lower temperature.
The two significant lipids of the red cell membrane are cholesterol and phospholipid. Cholesterol remains insoluble in water but solubilized by phospholipids both in the membrane and in the plasma lipoproteins.
Cholesterol also exchanges between membranes and lipoproteins. The amount of cholesterol establishes an equilibrium partition relative to phospholipid(C/PL) in these two compartments.
The conditions of C/Pl of the red cell membranes
The increase in the C/PL of the red cell membranes have been examined under three conditions:
- The unpredictable increase in vivo has been observed in the spurred cells of patients with severe liver disease.
- The administration of cholesterol-enriched diets to rodents and dogs induces the same red cells that have changed in vivo.
- The enriching of the C/PL of the lipoprotein environment with cholesterol-phospholipid dispersions has induced increased membrane cholesterol in vitro.
In each case, the C/PL of the plasma environment and the C/PL of the red cell membrane share a close relationship. In vivo, the C/PL of the red cell membrane’s mole ratio has a range of 0.9-1.0 to values which approach but fail to reach 2.0. However, this ratio can get 3.0 if in vitro.
The membrane lipid fluidity is directly influenced by the cholesterol enrichment of the red cell membrane. This is evaluated by the rotational diffusion of hydrophobic fluorescent probes such as diphenyl hexatriene(DPH).
Despite a correlation exists between increases in red cell membrane C/PL, the membrane fluidity over the range of membrane C/PL decreases from 1.0 to 2.0
The transformation of cell contour to one which is redundant and folded is associated with the cholesterol enrichment of red cell membranes.
This is also associated with a decrease in the red cell filterability in vitro. The cell shape is further modified to a spiny, irregular(spur) form when the Vivo circulation is present in the spleen.
Afterward, the survivability of cholesterol-rich red cells is decreased in the presence of the spleen. Several carrier-mediated transport pathways inhibit because active NA-K transport is not influenced by the cholesterol enrichment of the human red cells.
So, we can conclude that red cell membrane C/PL is sensitive to the C/PL of the plasma environment. If we increase the membrane C/PL, the membrane fluidity is decreased, and these changes are related to the reduction in membrane permeability.
The shortening survivability of the red cells in vivo is a distortion of cell contour and filterability.