[The A1- and non A1-effects of N6-(5-hydroxy-2-pyridyl)-methyl-adenosine on rat vas deferens].
N6-(5-hydroxy-2-pyridyl)-methyl-adenosine (HPMA) is a novel N6-substituted adenosine analogue recently obtained from Armillaria mellea (an edible fungus on which depends the growth of the famous Chinese traditional drug Gastrodia elata). It has been shown to have some characters of A1 receptor agonists of purinergic nerve. In this study, we compared the effects of HPMA with that of N6-Cyclohexyladenosine(CHA), an A1 selective agonist, on rat vas deferens in vitro, and found remarkable differences between them. In our study, HPMA dose-dependently decreased the contraction responses to exogenous Phenylephrine (PE), Norepinephrine (NE) and Acetylcholine(ACh) on rat vas deferens, while CHA showed no effect on these responses. 8-Cyclopentyl-1,3-dipropylxanthine(DPCPX), an A1 selective antagonist, did not show any influence on these effects of HPMA, indicating that the depression effect of HPMA may be through a non-A1 mechanism. Using HPMA to decrease about 50% of the twitch responses evoked by field-stimulation on rat vas deferens, the responsiveness to exogenous ACh seemed to be similar to that without HPMA pretreatment. These indicate that HPMA at this dosage (IC50 dosage) preferentially acted on presynapse (may be the A1 receptor) to attenuate the release of neurotransmitters. At a high dosage (10(-5) mol.L-1), HPMA abolished the neurogenic twitch responses evoked by electrical field-stimulation, while the responsiveness of rat vas deferens to exogenous ACh was decreased showing both pre-synapse and post-synapse depression.
Xiong
J
J
Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050.
Huang
J
J
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D017208:Rats, Wistar; D014649:Vas Deferens / Q000187:drug effects*
C469305:N(6)-(5-hydroxy-2-pyridyl)methyladenosine; D058906:Purinergic P1 Receptor Agonists; C027513:N(6)-cyclohexyladenosine; D000241:Adenosine