Physiologic antagonists

C. Quero et al.. Responses of male Hehcoverpa zea to single pulses of sex pheromone and behavioural antagonist. Physiological Entomology 26 (2001) 106-115. 

H3 Receptor Agonists and Antagonists Physiological Role of H3 Receptors... 

At low (1—10 nAf) concentrations ANP activates ANP whereas ANPg appears to be the physiological receptor for CNP. ANP and BNP are inactive at the latter subtype except at high micromolar concentrations. AP 811 [124833 5-OJ C gHggN 20g (58) is a selective ANP ligand. (L-a-Aminosuberic is an ANP antagonist. 

Potassium is required for enzyme activity in a few special cases, the most widely studied example of which is the enzyme pymvate kinase. In plants it is required for protein and starch synthesis. Potassium is also involved in water and nutrient transport within and into the plant, and has a role in photosynthesis. Although sodium and potassium are similar in their inorganic chemical behavior, these ions are different in their physiological activities. In fact, their functions are often mutually antagonistic. For example, increases both the respiration rate in muscle tissue and the rate of protein synthesis, whereas inhibits both processes (42). 

Calcium plays a vital role ia excitation—contraction coupling, and failure to maintain iatraceUular calcium homeostasis results ia ceU death. The avaUabUity of the calcium antagonists also provides a powerful tool for basic studies of excitation—contraction coupling, stimulus—excretion coupling, and other specific physiological functions. 

Dihydropyridines not only are intermediates for the synthesis of pyridines, but also are themselves an important class of N-heterocycles an example is the coenzyme NADH. Studies on the function of NADH led to increased interest in the synthesis of dihydropyridines as model compounds. Aryl-substituted dihy-dropyridines have been shown to be physiologically active as calcium antagonists. Some derivatives have found application in the therapy of high blood pressure and angina pectoris. For that reason the synthesis of 1,4-dihydropyridines has been the subject of intensive research and industrial use. The Hantzsch synthesis has thus become an important reaction. 

Antagonist, a molecule that interferes with the interaction of an agonist and a receptor protein or a molecule that blocks the constitutive elevated basal response of a physiological system. 

Ag, convention for the equilibrium dissociation constant of an antagonist-receptor complex usually determined in a functional assay denoting antagonism of a physiological response, although it can be associated with an antagonist when it is used in other types of experiment. It has units of M and is the concentration that occupies half the receptor population at equilibrium. It also can be thought of as the reciprocal of affinity. 

The interleukin-1 (EL-1) family of proteins currently comprises IL-1 a, IL-1 (3, and the IL-1 receptor antagonist (IL-1RA). The biological activities of EL-1 are shared by IL-1 a and IL-1 (3, whereas IL-1RA is a true receptor antagonist. IL-1 is a key player in acute and chronic inflammatory diseases. Whether IL-1 has a role in normal physiology is still unresolved. IL-1 can... 

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