Prostaglandin physiologic role

General physiological roles for fatty acids in cellular lipids are caloric storage, membrane fluidity, and prostaglandin precursors. The first of these mainly involved the formation and hydrolysis of triacyl glycerols, transport and activation of non-esterified fatty acids, and other steps leading to energy conversion (110). The second role primarily involves activation and incorporation into 1- and 2- positions of different phospholipids which form a major part of membranes. The third role is linked to the requirement for certain unsaturated fatty acids in the diets of most animals (110). 

PGE2 may also be involved in renal phosphate excretion, because exogenous PGE2 antagonizes the inhibition of phosphate resorption by parathyroid hormone in the proximal tubule. However, the physiologic role of this eicosanoid may be limited because the proximal tubule, the major site for phosphate transport, produces few prostaglandins. 

The physiologic role of prostaglandins in reproduction has been intensively studied since the discovery of prostaglandins in the seminal plasma of primates and sheep. It has been suggested that... 

Prostaglandin H synthase is the first enzyme involved in the arachidonic acid cascade . The prostaglandins can cause both relaxation and tension in smooth muscle and so have vital physiological roles. Prostaglandin H synthase acts as both a peroxidase and an oxygenase its so-called cyclooxygenase activity involves addition of two equivalents of oxygen to a free radical derived from arachidonic acid to form an endoperoxide... 

As additional information about the physiological role of NO is accumulated, new ideas and strategies for the use of NO donors are emerging. For example, several studies have demonstrated the importance of NO in penile erection (Rajfer et al., 1992 Burnett et al., 1992), and it is possible that selective delivery of NO, through the use of NO donors, may improve erectile function in impotent men. Stief etal. (1992) have shown that intracavernosal injections of 0.1-1 mg of linsidomine in patients with erectile dysfunction produced dose-dependent erectile responses with no systemic or local side effects. Porst (1993) has also shown linsidomine injection to be useful in producing penile erection, but not as effective as injected prostaglandin Ei. Further studies to optimize NO delivery for erectile responses appear to be warranted. 

Prostaglandins are compounds of related structures derived from long-chain fatty acids. They have a number of physiological roles, including control of smooth muscle contraction, development of inflammation, and inhibition of platelet aggregation. The last of these three roles makes them objects of research on ways to prevent heart disease. 

Linoleic acid is one of the most important polyunsaturated fatty acids it is the essential lipid precursor to many vital biomolecules, such as prostaglandins, thromboxanes, lipoxins, and prostacyclins (1-5). All of these linoleic acid metabolites are unique molecules with either carbocyclic systems containing chiral carbon centers or unsaturated C-C systems of specific geometric configurations. These fatty acid metabolites perform highly specialized physiologic roles (6,7). 

In spite of this bewildering complexity of biological actions of the prostaglandins, their roles in certain organs and/or physiological processes have been relatively well... 

The prostaglandins in the nervous system have been implicated to have physiological roles in temperature regulation, brain circulation and possibly in neuromodulation [201], The administration of prostaglandins of the E-series intraventricularly has been shown to have sedative effects in rodents and chickens [216]. In the mouse, a dose-dependent inhibition of picotoxin and pentahazol induced convulsion was observed [217,218]. In the cat prostaglandins inhibited penicillin induced seizures [219]. The mechanism of the anticonvulsive action of PGE compounds is not clear. 

Interest in the biosynthesis, metabolism and physiological roles of prostaglandins and related compounds has prompted extensive investigation of sensitive and selective analytical procedures. An early report in this area [302] described the preparation of TBDMS ethers of prostaglandin methyl esters and methyl ester-oximes by treating samples with 50 /il of TBDMCS (2 M in DMF) and 50 /il of imidazole (2 M in DMF) at 100 °C for 1 h). After cooling the, reaction mixture was applied to the top of a 0.5 X 3 cm column of Sephadex LH-20 swollen with heptane/ethyl acetate (3 1), and the derivatives were eluted with 4 ml of the same solvent. After evaporation of the solvent, samples were analysed by... 

There are many pharmaceutical preparations and biological compounds containing carboxylic group, i.e., fatty acids, prostaglandins, steroids, bile acids, a-keto acids, and glucuronic acid. These compounds play important physiological roles to achieve homeostasis. 

Horton EW, Poyser NL Uterine luteolytic hormone A physiological role for prostaglandin F2 0. Phys Rev (56) 595-65l,... 

Stanley-Samuelson, D.W. (1987) Physiological roles of prostaglandins and other eicosanoids in invertebrates. Biol. Bull. Woods Hole, 173,92-109... 

---