The EFFECTS OF 4‐AMINOPYRIDINE ON THE ISOLATED VAS DEFERENS AND ITS EFFECTS ON THE INHIBITORY PROPERTIES OF ADENOSINE, MORPHINE, NORADRENALINE AND Γ‐AMINOBUTYRIC ACID

Stone, T.W.

doi:10.1111/j.1476-5381.1981.tb16817.x

Cited by 27 publications

(10 citation statements)

References 22 publications

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“…Reports from other laboratories as well as from our own have already shown that GABAB receptors are widely distributed in the mammalian periphery. So far receptors with GABAB characteristics have been described in intestinal muscle (Kaplita, Waters & Triggle, 1982), atria vas deferens Stone, 1981), vascular muscle (Starke & Weitzell, 1981) and anoccocygeus muscle (Hughes, Mor- & Stone, 1982;Muyhaddin, Roberts & Woodruff, 1982a). They have also been demonstrated in the basilar artery (Anwar & Mason, 1982).…”

Section: Discussionmentioning

confidence: 99%

Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Bowery

Hill

Hudson

1983

British J Pharmacology

391

116

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Saturable binding of (±)‐[3H]‐baclofen and [3H]‐γ‐aminobutyric acid ([3H]‐GABA) to rat brain crude synaptic membranes has been examined by means of a centrifugation assay. The binding of [3H]‐baclofen could be detected in fresh or previously frozen tissue and was dependent on the presence of physiological concentrations of Ca2+ or Mg2+ although a lower affinity Na+‐dependent component could also be observed. Both components probably reflect binding to receptor recognition sites. The saturable portion of bound [3H]‐baclofen formed 20.3 ± 6.9% of total bound ligand. This could be displaced by GABA (IC50 =.0.04 μm), (−)‐baclofen (0.04 μm) and to a much lesser extent by (+)‐baclofen (33 μm). Isoguvacine, piperidine‐4‐sulphonic acid and bicuculline methobromide were inactive (up to 100 μm) and muscimol was only weakly active (IC50 = 12.3 μm). Saturable binding of [3H]‐GABA increased on adding CaCl2 or MgSO4 (up to 2.5 mm and 5.0 mm respectively) to the Tris‐HCl incubation solution. This binding (GABAB site binding) was additional to the bicuculline‐sensitive binding of GABA (GABAA site binding) and could be completely displaced by (−)‐baclofen (IC50 = 0.13 μm). Increasing the Ca2+ concentration (0 to 2.5 mm) increased the binding capacity of the membranes without changing their affinity for the ligand. The binding of [3H]‐GABA to GABAB sites could be demonstrated in fresh as well as previously frozen membranes with a doubling of the affinity being produced by freezing. Further incubation with the non‐ionic detergent Triton‐X‐100 (0.05% v/v) reduced the binding capacity by 50%. The pharmacological profile of displacers of [3H]‐GABA from GABAB sites correlated well with that for [3H]‐baclofen displacement. A correlation with data previously obtained in isolated preparations of rat atria and mouse vas deferens was also apparent. It is concluded that [3H]‐baclofen or [3H]‐GABA are both ligands for the same bicuculline‐insensitive, divalent cation‐dependent binding sites in the rat brain.

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Section: Discussionmentioning

confidence: 99%

Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Bowery

Hill

Hudson

1983

British J Pharmacology

391

116

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“…Contrary to expectation for an A2-receptor, Baer & Muller (1983) have claimed that in the guinea-pig taenia coli the adenosine analogues do not stimulate adenylate cyclase. It is also noteworthy that some actions of adenosine can be overcome by raising extracellular calcium (Silinsky, 1981;Stone, 1981;Schrader et al, 1975).…”

Section: Ion Studiesmentioning

confidence: 99%

Evidence that the P₁‐purinoceptor in the guinea‐pig taenia coli is an A₂‐subtype

Burnstock

Hills

Hoyle

1984

British J Pharmacology

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1 The effects of 5'-N-ethylcarboxamidoadenosine (NECA), L-NECA, 2-chloroadenosine, N6-phenylisopropyladenosine (L-PIA and D-PIA), cyclohexyladenosine (CHA), and adenosine were examined on the guinea-pig taenia coli. 2 All the analogues except L-NECA caused relaxations; the order of potency for the series was:3 L-PIA was twice as potent as D-PIA in inducing relaxations of the guinea-pig taenia coli. 4 Adenosine and its analogues that induce relaxation all caused a slow membrane hyperpolarization; differences in the rates of hyperpolarization and latencies were apparent, although not statistically significant. 5 The duration of the response to adenosine was significantly less than that for any adenosine analogue. 6 Ion studies, using the sucrose gap, revealed that responses to the analogues were attenuated in elevated extracellular potassium or reduced extracellular chloride. 7 8-Phenyltheophylline, a potent P1-purinoceptor antagonist, caused a rightward shift of all the adenosine and analogue concentration-response curves. 8 Dipyridamole, an adenosine uptake inhibitor, potentiated the relaxations to adenosine but had no significant effect on the relaxations induced by the analogues. 9 It is concluded that NECA, 2-chloroadenosine, L-PIA, CHA, D-PIA and adenosine mediate their relaxant effects via an extracellular P1-purinoceptor which displays characteristics of the A2-subtype as determined by the rank order of agonist potency. Electrophysiological analysis of the responses to each of the analogues did not reveal any marked differences in the modes of action even between NECA and L-PIA (preferential A2-and Al-receptor agonists, respectively).

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“…Therefore, it would be useful to clarify the contribution of these receptors to the inhibitory effects of the cannabinoid agonists in the vas deferens. Further studies are required to clarify whether anandamide and WIN 55,212‐2 exert their inhibitory effects on the rabbit vas deferens by acting through other types of non‐cannabinoid presynaptic receptors, for example purinergic receptors or receptors for GABA, 5‐hydroxytryptamine, dopamine or neuropeptide Y 30–34 …”

Section: Discussionmentioning

confidence: 99%

Effects of Cannabinoid Receptor Activation on Rabbit Bisected Vas Deferens Strips

Barun

Vural

Dileköz

et al. 2005

Clin Exp Pharma Physio

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1. In the present study, the effects of anandamide and WIN 55,212-2, cannabinoid receptor agonists, were investigated on electrical field stimulation (EFS)-induced biphasic twitch responses obtained from the epididymal and prostatic portions of rabbit vas deferens strips. 2. Anandamide and WIN 55,212-2 dose-dependently inhibited both the first and second phases of the EFS-induced twitch responses recorded from epididymal and prostatic portions of the vas deferens over the concentration range 10(-9) to 3 x 10(-6) mol/L. 3. The cannabinoid CB1 receptor antagonist AM 251 (10(-6) mol/L) and the cannabinoid CB2 receptor antagonist AM 630 (10(-6) mol/L) had no effect on the inhibitory action of anandamide on the biphasic twitch responses in the prostatic and epididymal portions of the rabbit vas deferens. 4. In both the prostatic and epididymal portions of the rabbit vas deferens, AM 251 significantly, but not completely, reversed the inhibitory effect of WIN 55,212-2 on the first phase of the twitch response. In contrast, AM 630 did not have any effect on the inhibitory action of WIN 55,212-2 in the rabbit vas deferens strips. 5. The inhibitory effects of anandamide or WIN 55,212-2 on EFS-induced twitch responses of both the prostatic and epididymal portions of the rabbit vas deferens were not altered in the presence of 10(-5) mol/L naloxone. 6. These results suggest that cannabinoid receptors may have a modulatory role in the regulation of sympathetic transmission in the rabbit vas deferens. However, further investigation is required to characterize the receptors involved.

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The EFFECTS OF 4‐AMINOPYRIDINE ON THE ISOLATED VAS DEFERENS AND ITS EFFECTS ON THE INHIBITORY PROPERTIES OF ADENOSINE, MORPHINE, NORADRENALINE AND Γ‐AMINOBUTYRIC ACID

Cited by 27 publications

References 22 publications

Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Evidence that the P₁‐purinoceptor in the guinea‐pig taenia coli is an A₂‐subtype

Effects of Cannabinoid Receptor Activation on Rabbit Bisected Vas Deferens Strips

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The EFFECTS OF 4‐AMINOPYRIDINE ON THE ISOLATED VAS DEFERENS AND ITS EFFECTS ON THE INHIBITORY PROPERTIES OF ADENOSINE, MORPHINE, NORADRENALINE AND Γ‐AMINOBUTYRIC ACID

Cited by 27 publications

References 22 publications

Characteristics of GABAB receptor binding sites on rat whole brain synaptic membranes

Characteristics of GABAB receptor binding sites on rat whole brain synaptic membranes

Evidence that the P1‐purinoceptor in the guinea‐pig taenia coli is an A2‐subtype

Effects of Cannabinoid Receptor Activation on Rabbit Bisected Vas Deferens Strips

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Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Characteristics of GABA_B receptor binding sites on rat whole brain synaptic membranes

Evidence that the P₁‐purinoceptor in the guinea‐pig taenia coli is an A₂‐subtype