Differential effects of fluoronorepinephrines on phosphatidylinositol turnover in rat pinealocytes.
(+/-)-Norepinephrines (NAs), substituted with fluorine at positions 2, 5, and 6 of the ring, were compared with the unsubstituted compound with respect to their capacity for eliciting increased incorporation of [32P]orthophosphate into phosphatidylinositol of pinealocytes. 5F-NA and 6F-NA were approximately equipotent with NA, whereas 2F-NA required a higher concentration and gave lower maximum stimulation. Inhibition of these effects by prazosin confirmed the participation of alpha 1-adrenergic receptors. The results are comparable with those reported for alpha 1-adrenergic receptor-mediated events in other systems and different from the beta-adrenergic receptor-mediated elevation of cyclic AMP in pinealocytes. These and earlier results emphasize the importance of the hydroxyl group at position 3 of the ring and at the beta-position of the side chain in catecholamine activation of the pineal alpha-adrenergic receptors, which are involved in alterations of phospholipid metabolism.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D009638:Norepinephrine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D010870:Pineal Gland / Q000378:metabolism*; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D013329:Structure-Activity Relationship
D010716:Phosphatidylinositols; D011942:Receptors, Adrenergic, alpha; C024882:3-fluoronorepinephrine; C024884:6-fluoronorepinephrine; D009638:Norepinephrine