Transient Receptor Potential Canonical 4 and 5 Channel Antagonist ML204 Depolarized Pacemaker Potentials of Interstitial Cells of Cajal

Background/Aims@#To investigate an effect of ML204 (an inhibitor of transient receptor potential canonical 4 and 5 [TRPC4/5] channels) on interstitial cells of Cajal (ICCs) and therefore determine whether TRPC4/5 channels act on ICC-generated pacemaker activity. @*Methods@#We enforced whole cell patch clamp analysis, measurements of the intracellular Ca2+ concentration, and reverse transcription polymerase chain reaction to determine the effect of ML204 (10 μM) or englerin A (a selective activator of TRPC4/5 channeles, 10 μM) and the existence of TRPC4/5 in mouse small intestinal ICC. @*Results@#Treatment of ICCs with ML204 or englerin A caused the membrane potentials to depolarize. This depolarization effect of membrane potentials by ML204 in ICCs was observed to be concentration-dependent. After treating Ca 2+ - and Na + -free solutions or flufenamic acid (a non-selective cation channel blocker), the pacemaker potentials in the ICCs were abolished. A specific anoctamin 1 channel blocker did not have any effect on the pacemaker activity in ML204-untreated control cells; however, they blocked ML204-induced pacemaker activity in ICCs. Specific primers designed against TRPC4 and TRPC5 detected the presence of TRPC4/5 in small intestinal ICCs, and the application of ML204 increased raise the frequency of Ca2+ oscillations in ICCs, as assessed using Fluo-4 AM. @*Conclusion@#The results implied that ML204 could not inhibit the pacemaker activity but depolarized the membrane potential of ICCs by regulating intracellular Ca2+oscillations and anoctamin 1 channels.

Comparison of wound healing effects between Oncorhynchus keta-derived polydeoxyribonucleotide (PDRN) and Oncorhynchus mykiss-derived PDRN

BACKGROUND: Polydeoxyribonucleotide (PDRN) influencing cellular growth and differentiation is recognized to promote wound healing by stimulating tissue repair. Although PDRN can be extracted from human placentas, PDRN medications have recently been extracted from the semen of trout (Oncorhynchus mykiss) and salmon (Oncorhynchus keta). The present study was designed to evaluate the wound healing effects of O. keta-derived PDRN for injection (Rejuvenex) and PDRN cream (Rejuvenex Cream) in comparison with those of O. mykiss-derived PDRN injection (Placentex). METHODS: Full-thickness skin defects were made on the back of mice (n=60). The mice were divided into the following four groups according to the dressing used for the wounds: O. mykiss-derived PDRN injection group, O. keta-derived PDRN injection group, O. keta-derived PDRN cream group, and normal saline soaked dressing group (control group). We analyzed the gross findings, wound sizes, histological findings, immunohistochemistry and enzyme-linked immunosorbent assays for the groups immediately after the treatment, and again after 4, 7, and 10 days of treatment. RESULTS: The wound healing effects were the greatest in the O. keta-derived PDRN injection and O. mykiss-derived PDRN injection groups, which showed similar scores, followed by the O. keta-derived cream and normal saline soaked dressing groups. CONCLUSION: The injection of PDRN extracted from O. keta was found to be as effective at healing full-thickness skin defects as the O. mykiss-derived PDRN injection, which is currently used in the clinic. Moreover, the O. keta-derived PDRN injection was also found to reduce the time required for wound healing.

Effects of corticotropin-releasing hormone on the expression of adenosine triphosphate-sensitive potassium channels (Kir6.1/SUR2B) in human term pregnant myometrium

OBJECTIVE: Corticotropin-releasing hormone (CRH) is a crucial regulator of human pregnancy and parturition. Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels are important for regulating myometrial quiescence during pregnancy. We investigated regulatory effects of different concentrations of CRH on KATP channel expression in human myometrial smooth muscle cells (HSMCs) in in vitro conditions. METHODS: After treating HSMCs with different concentrations of CRH (1, 10, 102, 103, 104 pmol/L), mRNA and protein expression of KATP channel subunits (Kir6.1 and SUR2B) was analyzed by reverse transcription-polymerase chain reaction and western blot. We investigated which CRH receptor was involved in the reaction and measured the effects of CRH on intracellular Ca2+ concentration when oxytocin was administered in HSMCs using Fluo-8 AM ester. RESULTS: When HSMCs were treated with low (1 pmol/L) and high (103, 104 pmol/L) CRH concentrations, KATP channel expression significantly increased and decreased, respectively. SUR2B mRNA expression at low and high CRH concentrations was significantly antagonized by antalarmin (CRH receptor-1 antagonist) and astressin 2b (CRH receptor-2 antagonist), respectively; however, Kir6.1 mRNA expression was not affected. After oxytocin treatment, the intracellular Ca2+ concentration in CRH-treated HSMCs was significantly lowered in low concentration of CRH (1 pmol/L), but not in high concentration of CRH (103 pmol/L), compared to control. CONCLUSION: Our data demonstrated the regulatory effect was different when HSMCs were treated with low (early pregnancy-like) and high (labor-like) CRH concentrations and the KATP channel expression showed significant increase and decrease. This could cause inhibition and activation, respectively, of uterine muscle contraction, demonstrating opposite dual actions of CRH.