Participation of cAmp in Low pO2 Chemotransduction in the Carotid Body
The carodit bodies (c.b.) are arterial chemoreceptors which by sensing blood pO2 and pH originate ventilatory reflexes directed to bring those blood parameters to normality. Structurally, the c.b. are formed by clusters of cells separated from each other by thin walls of connective tissue. Two types of cells are present in the clusters, type-I or chemoreceptor and type-II or sustentacular; the former cellular type exhibits a great number of dense-core vesicles and is known to contain a variety of neurotransmitters including dopamine (DA), norepinephrine (NE), acetylcholine (Ach), and different neuropeptides (met- and leu-enkephalins, substance P, and dynorphin) and contacts synaptically with the sensory fibers of the carotid sinus nerve (c.s.n.) (Fidone and Gonzalez, 1986). Type-II cells lack specialized organelles in their cytoplasms and are considered supportive elements with a glial-like function (Kondo et al., 1982). This structural organization and the available neurochemical data (see Fidone and Gonzalez, 1986) configurate the c.b. as composite receptors in which type-I cells detect the blood-born stimuli and respond releasing different neurotransmitters capable of setting the level of activity in the c.s.n. (Gonzalez et al., 1989).
KeywordsAdenylate Cyclase cAMP Level Carotid Body cAMP Content Increase cAMP Level
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