title: Smooth muscle and purinergic contraction of the human, rabbit, rat, and mouse testicular capsule.
abstract: The smooth-muscle cells of the testicular capsule (tunica albuginea) of man, rat, and mouse were examined by electron microscopy. They were characteristically flattened, elongated, branching cells and diffusely incorporated into the collagenous matrix and did not form a compact muscle layer. Contractile and synthetic smooth-muscle cell phenotypes were identified. Nerve varicosities in close apposition to smooth muscle were seen in human tissue. Contractions induced by adenosine 5'-triphosphate (ATP), alpha, beta-methylene ATP, noradrenaline (NA), acetylcholine (ACh), and electrical field stimulation (EFS) of autonomic nerves were investigated. Nerve-mediated responses of the rabbit and human tunica albuginea were recorded. The EFS-induced human responses were completely abolished by prazosin. In the rabbit, EFS-induced contractile responses were reduced by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid by 36% and by prazosin by 77%. Both antagonists together almost completely abolished all EFS-induced contractions. The human tunica albuginea was contracted by NA, ATP, and alpha, beta-methylene ATP, but not by ACh. The rabbit and rat tunica albuginea were contracted by NA, ATP, alpha, beta-methylene ATP, and ACh. The mouse tunica albuginea was contracted by ACh, ATP, and alpha, beta-methylene ATP, but relaxed to NA. Immunohistochemical studies showed that P2X1 (also known as P2RX1) and P2X2 (also known as P2RX2) receptors were expressed on the smooth muscle of the rodent testicular capsule, expression being less pronounced in man. The testicular capsule of the rat, mouse, rabbit, and man all contain contractile smooth muscle. ATP, released as a cotransmitter from sympathetic nerves, can stimulate the contraction of rabbit smooth muscle. Human, rat, and mouse testicular smooth muscle demonstrated purinergic responsiveness, probably mediated through the P2X1 and/or P2X2 receptors.
authors.affiliation: Autonomic Neuroscience Centre, Royal Free Hospital, London NW3 2PF, United Kingdom.
authors.forename: Frederick C L
authors.initials: FC
authors.lastname: Banks
authors.forename: Gillian E
authors.initials: GE
authors.lastname: Knight
authors.forename: Robert C
authors.initials: RC
authors.lastname: Calvert
authors.forename: Mark
authors.initials: M
authors.lastname: Turmaine
authors.forename: Cecil S
authors.initials: CS
authors.lastname: Thompson
authors.forename: Dimitri P
authors.initials: DP
authors.lastname: Mikhailidis
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Morgan
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Burnstock
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology; D004558:Electric Stimulation; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000294:innervation / Q000502:physiology* / Q000648:ultrastructure; D009638:Norepinephrine / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology*; D013737:Testis / Q000294:innervation / Q000502:physiology*
chemical_list: D010975:Platelet Aggregation Inhibitors; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018047:Receptors, Purinergic P1; D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D000109:Acetylcholine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine