Abstract
Immunohistochemical studies demonstrated abundant P2X(1)-receptor immunoreactivity colocalized with alpha-actin within the fibromuscular stroma of the guinea pig prostate. P2X(2)-, P2X(3)- and P2X(4)-receptor immunoreactivity was absent. alphabetamethylene Adenosine 5'-triphosphate (ATP) attenuated contractile responses to electrical field stimulation (50 V, 0.5 ms, 5-20 Hz) in the absence and presence of prazosin (0.3 microM). Responses to 1-2 Hz were unaffected. ARL 67156 (6-N, N-diethyl-beta-gamma-dibromomethylene-D-adenosine-5-triphosphate; 100 microM) enhanced contractile responses to electrical field stimulation (50 V, 0.5 ms, 10-20 Hz). Concentration-response curves to exogenously applied ATP analogues on unstimulated preparations elicited concentration-dependent suramin (100 microM)-sensitive contractions. The rank order of potency was: alphabetamethylene ATP>2methylthio ATP=betagammamethylene ATP>adenosine 5'-diphosphate (ADP)=ATP. Adenosine and adenosine 5'-monophosphate (AMP) did not produce contractile responses. These results demonstrate the presence of functional P2X(1)-receptors within the fibromuscular stroma of the guinea pig prostate and suggest a cotransmitter role for ATP with noradrenaline during high-frequency stimulation.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / analysis
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Adenosine Diphosphate / pharmacology
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Adenosine Triphosphatases / antagonists & inhibitors
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Adenosine Triphosphate / analogs & derivatives*
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Adenosine Triphosphate / metabolism
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Adenosine Triphosphate / pharmacology*
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Adenosine Triphosphate / physiology
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Animals
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Atropine / pharmacology
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Dose-Response Relationship, Drug
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Electric Stimulation
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Guinea Pigs
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Immunohistochemistry / methods
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In Vitro Techniques
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Male
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Muscle Contraction / drug effects
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Muscle, Smooth / drug effects*
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Muscle, Smooth / metabolism
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Muscle, Smooth / physiology
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Norepinephrine / metabolism
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Norepinephrine / physiology*
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Prazosin / pharmacology
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Prostate / drug effects*
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Prostate / metabolism
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Prostate / physiology
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Receptors, Purinergic P2 / analysis
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Receptors, Purinergic P2X
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Receptors, Purinergic P2X2
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Receptors, Purinergic P2X4
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Suramin / pharmacology
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Tetrodotoxin / pharmacology
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Thionucleotides / pharmacology
Substances
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6-N,N-diethyl-beta,gamma-dibromomethylene-D-ATP
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Actins
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Receptors, Purinergic P2
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Receptors, Purinergic P2X
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Receptors, Purinergic P2X2
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Receptors, Purinergic P2X4
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Thionucleotides
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Tetrodotoxin
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Suramin
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Adenosine Diphosphate
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Atropine
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Adenosine Triphosphate
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Adenosine Triphosphatases
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alpha,beta-methyleneadenosine 5'-triphosphate
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Norepinephrine
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Prazosin
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2-methylthio-ATP