Phentolamine mesylate relaxes penile corpus cavernosum tissue by adrenergic and non-adrenergic mechanisms.
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Traish A, Gupta S, Gallant C, Huang YH, Goldstein I
Phentolamine mesylate relaxes penile corpus cavernosum tissue by adrenergic and non-adrenergic mechanisms.
Int J Impot Res. 1998 Dec;10(4):215-23. doi: 10.1038/sj.ijir.3900351.
- PubMed ID
- 9884917 [ View in PubMed]
- Abstract
AIM OF THE STUDY: We investigated the biochemical and physiological mechanisms of action of phentolamine mesylate (Vasomax) in regulating erectile tissue smooth muscle contractility in human and rabbit corpus cavernosum. METHODS: The binding activity of phentolamine was investigated in a cell-free system by displacement of specific and selective radiolabelled ligands to alpha 1 and 2 adrenergic receptors. The physiologic activity of phentolamine-mediated relaxation of adrenergic and non-adrenergic pre-contracted erectile tissue strips of human and rabbit corpus cavernosum were studied in organ bath chambers. RESULTS: In corpus cavernosum membranes, phentolamine displaced binding of the selective alpha 1 receptor antagonists [125I]HEAT and [3H]prazosin and the alpha 2 receptor antagonists [3H]rauwolscine and [3H]RX 821002 with relatively high affinity. Phentolamine caused concentration dependent relaxation in erectile tissue strips pre-contracted with adrenergic agonists phenylephrine, norepinephrine, oxymetazoline and UK 14,304, as well as with non-adrenergic contractile agents endothelin and KCl. Biochemical and physiologic studies reveal that the concentration of phentolamine required to displace half maximal binding or to produce half-maximal relaxation was similar to that found in human plasma 30 min after ingestion of 40 mg of Vasomax. Reversible inhibition of nitric oxide synthase by L-nitroarginine or mechanical disruption of endothelium diminished non-adrenergic phentolamine-mediated erectile tissue relaxation. CONCLUSIONS: Phentolamine mesylate induced relaxation of corpus cavernosum erectile tissue by direct antagonism of alpha 1 and 2 adrenergic receptors and by indirect functional antagonism via a non-adrenergic, endothelium-mediated mechanism suggesting nitric oxide synthase activation.
DrugBank Data that Cites this Article
- Drug Targets
Drug Target Kind Organism Pharmacological Action Actions Phentolamine Alpha-1 adrenergic receptors (Protein Group) Protein group Humans YesAntagonistDetails Phentolamine Alpha-2 adrenergic receptors (Protein Group) Protein group Humans UnknownAntagonistDetails