The subtypes of alpha-adrenoceptors which mediate pressor responses to sympathomimetic agonists or to nerve stimulation in pithed rabbits have been classified according to the effects of 'selective' antagonists and a comparison has been made, for the alpha 2-subtype, with corresponding responses in the rat. In the rabbit the dose-response curve for phenylephrine was shifted to the right in parallel by prazosin (1 mg kg-1) and was unaffected by rauwolscine (1 mg kg-1). The dose-response curve for noradrenaline was shifted to the right by prazosin (1 mg kg-1) and was shifted to a smaller extent by rauwolscine (1 mg kg-1) or imiloxan (10 mg kg-1). After rauwolscine, prazosin produced a rightward shift larger than when given alone. After prazosin, rauwolscine produced a rightward shift larger than when given alone. The responses to pressor nerve stimulation at low frequencies (less than 1 Hz) could be reduced by prazosin, rauwolscine or imiloxan but those at a higher frequency could be reduced only by prazosin. These results indicate that the responses to noradrenaline or to nerve stimulation are mediated by both alpha 1- and alpha 2-adrenoceptors. Low doses or frequencies have a proportionately greater component which is alpha 2. ...Continue Reading
Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.