P2Y receptor-mediated transient relaxation of rat longitudinal ileum preparations involves phospholipase C activation, intracellular Ca(2+) release and SK channel activation.

AIM: Purinergic signaling plays a major role in the enteric nervous system, where it governs gut motility through a number of P2X and P2Y receptors. The aim of this study was to investigate the P2Y receptor-mediated motility in rat longitudinal ileum preparations. METHODS: Ileum smooth muscle strips were prepared from rats, and fixed in an organ bath. Isometric contraction and relaxation responses of the muscle strips were measured with force transducers. Drugs were applied by adding of stock solutions to the organ bath to yield the individual final concentrations. RESULTS: Application of the non-hydrolyzable P2 receptor agonists α,ß-Me-ATP or 2-Me-S-ADP (10, 100 µmol/L) dose-dependently elicited a transient relaxation response followed by a sustained contraction. The relaxation response was largely blocked by SK channel blockers apamin (500 nmol/L) and UCL1684 (10 µmol/L), PLC inhibitor U73122 (100 µmol/L), IP3 receptor blocker 2-APB (100 µmol/L) or sarcoendoplasmic Ca(2+) ATPase inhibitor thapsigargin (1 µmol/L), but not affected by atropine, NO synthase blocker L-NAME or tetrodotoxin. Furthermore, α,ß-Me-ATP-induced relaxation was suppressed by P2Y1 receptor antagonist MRS2179 (50 µmol/L) or P2Y13 receptor antagonist MRS2211 (100 µmol/L), and was abolished by co-application of the two antagonists, whereas 2-Me-S-ADP-induced relaxation was abolished by P2Y6 receptor antagonist MRS2578 (50 µmol/L). In addition, P2Y1 receptor antagonist MRS2500 (1 µmol/L) not only abolished α,ß-Me-ATP-induced relaxation, but also suppressed 2-Me-S-ADP-induced relaxation. CONCLUSION: P2Y receptor agonist-induced transient relaxation of rat ileum smooth muscle strips is mediated predominantly by P2Y1 receptor, but also by P2Y6 and P2Y13 receptors, and involves PLC, IP3, Ca(2+) release and SK channel activation, but is independent of acetylcholine and NO release.

Age-related decrease of adenosine-mediated relaxation in rat detrusor is a result of A2B receptor downregulation.

OBJECTIVES: To analyze the effect of adenosine on detrusor smooth muscle contraction and to assess age-related changes of adenosine function. METHODS: Sustained contractions were induced in young (10-30 days) and old (>60 days) rat detrusor muscle strips by application of 30 mmol/L K(+) and adenosine (0.1-400 µmol/L), which was either applied before raising the K(+) concentration or added to the precontracted muscle strip. Quantitative polymerase chain reaction analyses were used to study adenosine receptor expression in rat and human detrusor specimens. RESULTS: Pretreatment with adenosine dose-dependently reduced subsequent K(+) -induced contraction in detrusor muscle strips from young rats (half-maximal effect = 40 µmol/L). The residual depolarization-induced contraction strength in young tissue was significantly smaller than in tissue from old animals, showing a greater potency of adenosine in young detrusor samples. Likewise, the relaxing effect of adenosine on precontracted detrusor muscle was also significantly more pronounced in young compared with older detrusor. Quantitative polymerase chain reaction showed an age-related downregulation of the adenosine A2B receptor in rat detrusor tissues, which could be confirmed in human detrusor samples. Furthermore, relaxation of both K(+) -induced as well as carbachol-induced contraction by the specific A2B receptor agonist BAY 60-6583 was significantly more pronounced in young than in old rats. CONCLUSIONS: Adenosine powerfully counteracts contraction of detrusor smooth muscle, which is lost in the aging bladder. This is paralleled by an age-dependent transcriptional downregulation of the low-affinity A2B receptor. Hence, this might be pathophysiologically relevant in conditions of raised adenosine concentrations, such as hyperactive bladder contractility.

A new species of Cylindrophis Wagler, 1828 (Reptilia: Squamata: Cylindrophiidae) from Boano Island, northern Maluku Province, Indonesia.

 We describe a new species of snake of the genus Cylindrophis Wagler, 1828 from Boano Island, northern Maluku         Province, Indonesia. Cylindrophis osheai sp. nov. differs from all congeners by a combination of the following eidonomic characters: (1) 19 dorsal scale rows at midbody; (2) 224-226 ventral scales; (3) 8-9 subcaudal scales; (4) 25-28 dark ventral blotches, aligned to form a broad, wavy stripe along most of the body; (5) a dark ventral pattern that is completely separated from the dark dorsal coloration; (6) an almost completely dark ventral surface on the tail; (7) a dark bar running from the eye through the 3rd and 4th supralabials to the mouth; and (8) a dark, double-diamond-shaped ventral blotch in the area immediately posterior to the genials. Eidonomic species separation from other Cylindrophis species is supported by differences in cranial osteology, as elucidated by micro-computed tomography images. Diagnostic features of the cranium include (1) well-developed postorbitofrontals that project laterally beyond the maxilla in dorsal view, creating a characteristic, horn-like appearance; (2) a broad parietal with a bulbous middle section; (3) 10-12 maxillary teeth; (4) nine        palatine teeth; (5) 7-9 teeth on the pterygoid; and (6) 11-13 teeth on the dentary. We also provide notes on the taxonomic history of Cylindrophis melanotus Wagler, 1828 and an identification key to the Moluccan species of the genus.

Hyperpolarization-Activated Cyclic Nucleotide-Gated Non-selective (HCN) Ion Channels Regulate Human and Murine Urinary Bladder Contractility.

Purpose: Hyperpolarization-activated cyclic nucleotide gated non-selective (HCN) channels have been demonstrated in the urinary bladder in various species. Since they play a major role in governing rhythmic activity in pacemaker cells like in the sinoatrial node, we explored the role of these channels in human and murine detrusor smooth muscle. Methods: In an organ bath, human and murine detrusor smooth muscle specimens were challenged with the HCN channel blocker ZD7288. In human tissue derived from macroscopically tumor-free cancer resections, the urothelium was removed. In addition, HCN1-deficient mice were used to identify the contribution of this particular isoform. Expression of HCN channels in the urinary bladder was analyzed using histological and ultrastructural analyses as well as quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Results: We found that the HCN channel blocker ZD7288 (50 µM) both induced tonic contractions and increased phasic contraction amplitudes in human and murine detrusor specimens. While these responses were not sensitive to tetrodotoxin, they were significantly reduced by the gap junction inhibitor 18ß-glycyrrhetic acid suggesting that HCN channels are located within the gap junction-interconnected smooth muscle cell network rather than on efferent nerve fibers. Immunohistochemistry suggested HCN channel expression on smooth muscle tissue, and immunoelectron microscopy confirmed the scattered presence of HCN2 on smooth muscle cell membranes. HCN channels seem to be down-regulated with aging, which is paralleled by an increasing effect of ZD7288 in aging detrusor tissue. Importantly, the anticonvulsant and HCN channel activator lamotrigine relaxed the detrusor which could be reversed by ZD7288. Conclusion: These findings demonstrate that HCN channels are functionally present and localized on smooth muscle cells of the urinary bladder. Given the age-dependent decline of these channels in humans, activation of HCN channels by compounds such as lamotrigine opens up the opportunity to combat detrusor hyperactivity in the elderly by drugs already approved for epilepsy.

A new species of bent-toed gecko, genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata: Gekkonidae), from Jawa Timur Province, Java, Indonesia, with taxonomic remarks on C. fumosus (Müller, 1895).

A new species of the gekkonid lizard genus Cyrtodactylus Gray, 1827 is described from Klakah, Lumajang Regency, Jawa Timur Province, Java, Indonesia. Cyrtodactylus klakahensis sp. nov. can be distinguished from all other congeners by the presence of (1) a deep precloacal groove in males, (2) three rows of enlarged precloacofemoral scales, of which the third row bears 37-38 pores in males, (3) three or four rows of enlarged scales between the precloacofemoral scale rows and the cloaca, forming distinct chevrons, (4) raised and strongly keeled dorsal tubercles in 15-19 rows at midbody, (5) an indistinct lateral fold, (6) 17-20 subdigital lamellae under the 4th toe, and (7) subcaudal scales which are not transversely enlarged. Cyrtodactylus klakahensis sp. nov. is only the third bent-toed gecko species described from Java, indicating that the diversity of this genus on this island has been neglected in the past. Furthermore, we confirm that C. fumosus (Müller, 1895) is a species that possesses a precloacal groove in males and is most likely restricted to northern Sulawesi. That species is defined by a single female holotype (NMB-REPT 2662). Specimens in museum collections catalogued as C. fumosus from localities elsewhere are misidentified and likely represent undescribed species.