Dopaminergic modulation of human adrenal medulla: indirect evidence for the involvement of DA-2 receptors located on the chromaffin cells.
1. Pharmacological blockade of DA-2 receptors causes a significantly higher epinephrine (E) response to physical exercise in normal man. 2. The present study was undertaken to evaluate whether dopaminergic modulation of E secretion is present also for a stimulus such as glucagon which acts directly on chromaffin cells. 3. Seven normal males were studied in a single blind randomized manner on two separate occasions, after pre-treatment with placebo or domperidone (DMP; 20 mg orally). Plasma E and norepinephrine, plasma prolactin, heart rate and blood pressure were measured on two separate occasions (placebo vs DMP) before and after a glucagon (1 mg i.v.) stimulation test. 4. Glucagon caused an increase in plasma E either after placebo (P = 0.043) or after domperidone (P = 0.012). DMP administration caused a significant increase in plasma E (P = 0.0008). Absolute increase in plasma E after glucagon was significantly higher after DMP than after placebo (P = 0.030). 5. As the dopaminergic modulation of human adrenal medulla is confirmed also for a stimulus acting directly on chromaffin cells, the results of the present study suggest that the DA-2 receptors responsible for the modulation are located on medullary cells.
Mannelli
M
M
Divisione di Endocrinologia e Malattie del Metabolismo, Universitá di Firenze, Italia.
Lanzillotti
R
R
Ianni
L
L
Pupilli
C
C
Serio
M
M
D000313:Adrenal Medulla / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D000328:Adult; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000494:pharmacology; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology; D017448:Receptors, Dopamine D2
D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D004294:Domperidone; D005934:Glucagon; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine