[Studies of the mechanism of lowering intraocular pressure on Erycibele alkaloid].
OBJECTIVE
To investigate the molecular pharmacological mechanism of lowering intraocular pressure of Erycibele alkaloid.


METHODS
Rabbit pupil diameter was measured by a pupillary ruler in constant illumination and the intraocular pressure (IOP) was measured by pneumatonometer. Iris contracting force was measured in an experiment of isolated rabbit iris. Radioimmune method was used to determine the content of cyclonucleotide.


RESULTS
The pD(2) value (the affinity to M-receptors of agonist) of Erycibele alkaloid's miosis is 3.60 +/- 0.15 and its IOP lowering action is 3.49 +/- 0.07. In the isolated iris contracting experiment, its pD(2) value is 6.38 +/- 0.12. M(3) receptor antagonist is the strongest antagonist in inhibiting the miosis, IOP lowering action and isolated iris pupillary contracting action of Erycibele alkaloid. 0.01% Erycibele alkaloid can cause the decrease of cAMP and the increase of cGMP in the aqueous humor.


CONCLUSIONS
The effects of miosis and IOP lowering of Erycibele alkaloid are all mediated by M(3) receptor subtype and its signal transductive mechanism is connected with cyclic nucleotide system.
Zeng
S
S
Department of Pharmacology, Sun Yat-sun University of Medical Sciences, Guangzhou 510089.
Zhang
Y
Y
Peng
D
D
Wu
Y
Y
Yu
K
K
Zhou
W
W
D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000008:administration & dosage / Q000494:pharmacology*; D007429:Intraocular Pressure / Q000187:drug effects*; D018721:Muscarinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D009883:Ophthalmic Solutions; D011680:Pupil / Q000187:drug effects; D011817:Rabbits; D043587:Receptor, Muscarinic M3 / Q000187:drug effects*; D014326:Tropanes / Q000008:administration & dosage / Q000494:pharmacology
D019086:Bridged Bicyclo Compounds, Heterocyclic; D018721:Muscarinic Agonists; D009883:Ophthalmic Solutions; D043587:Receptor, Muscarinic M3; D014326:Tropanes; C027863:bao gong teng A