Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.17 (adenosine deaminase)
 5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methoxamine and phenylephrine (PE), postsynaptic alpha adrenergic agonists stimulated the accumulation of cyclic AMP in spinal cord tissue slices. Naphazoline, oxymetazoline and clonidine, previously shown to have greater efficacy at presynaptic alpha receptors did not alter accumulation and, in fact, blocked the PE response. The PE-stimulation was completely inhibited by postsynaptic alpha antagonists, incompletely by agents which bl ock presynaptic alpha receptors, and slightly by the beta blocker propranolol. Pe-stimulated accumulation was potentiated by phosphodiesterase inhibition (RO 20-1724). In contrast to previous reports on the requirement of the copresence of adenosine for alpha receptor stimulated accumulation of cyclic AMP in neuronal tissue, the PE-stimulation in spinal cord slices was unchanged by adenosine receptor blockade (theophylline), hydrolysis of endogenous adenosine (adenosine deaminase), inhibition of adenosine deaminase (EHNA) or blockade of adenosine uptake (dipyridamole). Added adenosine increased basal accumulation and produced a marked potentiation of the PE response. From this data it is evident that, in spinal cord tissue slices, there occurs a postsynaptic alpha adrenergic receptor linked to cyclic AMP accumulation which does not require the presence of other neurohumoral agents for activation.
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PMID:Alpha adrenergic receptor mediated formation of cyclic AMP in rat spinal cord. 610 25

1. The effect of methoxamine, an alpha1-adrenoceptor agonist, on the overflow of endogenous noradrenaline (NA) was examined in the electrically field stimulated (EFS) caudal artery obtained from Wistar rats, Wistar-Kyoto rats (WKY) and age-matched spontaneously hypertensive rats (SHR). 2. Methoxamine inhibited the EFS-evoked release of endogenous NA in the arteries from Wistar rats and WKY, but not in the arteries of SHR. 2-chloroadenosine, a purinoceptor agonist, also inhibited the NA release in the arteries from normotensive rats but not in the arteries of SHR. 3. The inhibitory effect of methoxamine was blocked by adenosine deaminase and potentiated by adenosine uptake inhibitor, dipyridamole. 4. Methoxamine caused the release of adenine nucleotides and adenosine from the caudal arteries of WKY and SHR. 5. These suggest that the inhibitory effect of methoxamine on NA release is mediated by endogenous adenyl purines and that the failure of methoxamine to inhibit NA release in the caudal artery of SHR is due to a dysfunction of the prejunctional purinoceptors on sympathetic nerve terminals.
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PMID:Effect of methoxamine on noradrenaline release in the caudal artery of hypertensive rats. 907 56