Adenosine 5'-triphosphate (ATP) is an excitatory cotransmitter with noradrenaline to the smooth muscle of the rat prostate gland.
1. This study investigated whether adenosine 5'-triphosphate (ATP) is involved in neurotransmission to the rat prostate gland. 2. Fluorescence immunohistochemistry carried out on formaldehyde-fixed and frozen sections of rat prostate showed immunoreactivity for the P2X(1)-receptor in the fibromuscular stroma surrounding the secretory acini but not in the glandular epithelium. P2X(2)-, P2X(3)-, P2X(4)- and P2X(7)-receptors were immunonegative in the rat prostate stroma. Double-staining procedures showed P2X(1)-receptor immunoreactivity to be colocalized with alpha-actin immunoreactivity. 3. Isolated organ bath studies investigated whether drugs, which modify purinergic mechanisms, are able to affect contractility of the rat prostate gland. Suramin (100 micro M) and alphabetamethylene ATP (10 micro M) inhibited contractile responses to trains of electrical-field stimulation (70 V, 0.5 ms, 0.1-2 Hz) in the absence and presence of prazosin (300 nM). Responses to 5-20 Hz were unaffected by suramin or alphabetamethylene ATP. 4. Exogenous application of ATP analogues to unstimulated isolated preparations of rat prostate produced concentration-dependent suramin (100 micro M) sensitive transient contractions with a relative order of potency: alphabetamethylene ATP>betagammamethylene ATP>ATP. 5. Adenosine and adenosine 5'-monophosphate (AMP) did not produce contractile responses. 6. These results suggest that P2X(1)-receptors for ATP, which mediate contractions are present in the fibromuscular stroma of the rat prostate. The relative order of potency of ATP analogues in producing contractions of the rat prostate is consistent with the activation of P2X(1)-receptors. Inhibition by suramin and alphabetamethylene ATP of electrically evoked nerve-mediated contractions of the rat prostate implies that ATP contributes to this contractile response and is therefore a cotransmitter with noradrenaline during low-frequency stimulation.
Ventura
Sabatino
S
Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia. Sab.Ventura@vcp.monash.edu.au
Dewalagama
Ramila K
RK
Lau
Linda C L
LC
D000255:Adenosine Triphosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D007150:Immunohistochemistry; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009411:Nerve Endings / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000494:pharmacology* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D011224:Prazosin / Q000008:administration & dosage; D011467:Prostate / Q000187:drug effects / Q000502:physiology; D011685:Purine Nucleotides / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011983:Receptors, Purinergic / Q000187:drug effects; D018048:Receptors, Purinergic P2 / Q000187:drug effects* / Q000502:physiology; D013498:Suramin / Q000008:administration & dosage
D018377:Neurotransmitter Agents; D011685:Purine Nucleotides; D011983:Receptors, Purinergic; D018048:Receptors, Purinergic P2; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine; D011224:Prazosin