Myometrial relaxation of mice via expression of two pore domain acid sensitive K⁺ (TASK-2) channels

Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K⁺ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K⁺ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K⁺ channels (TASK-2). NIOK in the presence of K⁺ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.

Mechanism of Relaxation Via TASK-2 Channels in Uterine Circular Muscle of Mouse

Plasma pH can be altered during pregnancy and at labor. Membrane excitability of smooth muscle including uterine muscle is suppressed by the activation of K+ channels. Because contractility of uterine muscle is regulated by extracellular pH and humoral factors, K+ conductance could be connected to factors regulating uterine contractility during pregnancy. Here, we showed that TASK-2 inhibitors such as quinidine, lidocaine, and extracellular acidosis produced contraction in uterine circular muscle of mouse. Furthermore, contractility was significantly increased in pregnant uterine circular muscle than that of non-pregnant muscle. These patterns were not changed even in the presence of tetraetylammonium (TEA) and 4-aminopyridine (4-AP). Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretchactivated channels in myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed increased immunohistochemical expression of TASK-2. Therefore, TASK-2, seems to play a key role during regulation of myometrial contractility in the pregnancy and provides new insight into preventing preterm delivery.

Effects of Advanced Glycation End Products on Rat Bladder Fibroblast / 대한비뇨기과학회지

PURPOSE: The products of the irreversible non-enzymatic glycation is one of the important toxic components and it is called advanced glycation end products (AGEs). Because AGEs is related to development of neural toxicities, this study is directed to investigate the direct effects of AGEs on the rat bladder fibroblast cells in vitro. MATERIALS AND METHODS: Fibroblast cells were cultured, using Sprague Dawley rat bladder. AGEs-bovine serum albumin (AGEs-BSA) was prepared, characterized by spectrophotometry, SDS-PAGE and ELISA. The viability of the fibroblast cells after AGEs-BSA treatment was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. Receptor of advanced glycation end products (RAGE), procollagen type I, procollagen type III, and TGF-beta1, 2, 3 mRNA expression levels were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and RNA PCR-Southern blotting. RESULTS: Fibroblast cells were proliferated by high dose AGE (2,200nmol, p<0.05, statistical analysis by ANOVA). RAGE mRNA expression was confirmed in bladder fibroblast in vitro. Procollagen type I mRNA expression levels were increased by high dose AGEs (1,100, 2,200nmol FFI) treatment at 24 hours and 48 hours. TGF-beta2 mRNA expression levels were increased dose dependently at 72 hours. TGF-beta3 mRNA expression levels were suppressed in high dose AGEs treated cells from 24 hours. CONCLUSIONS: AGEs increase procollagen type I mRNA, TGF-beta2, TGF-beta3 mRNA expression and proliferative activity of the bladder fibroblast cells in vitro. These results suggest that AGEs can direct toxic effects to bladder mesenchymal cell proper.

Expression of Human Beta-Defensin in Human Male Urogenital Organs / 감염

BACKGROUND: Defensins are small (3.5~5 kDa) cationic antimicrobial peptides that have a broad spectrum of activity that includes gram-negative bacterias, yeasts and enveloped viruses. The defensins contain six cysteine residues forming three disulfide bridges depending on the spacing of the cysteine residues and the connectivity of the disulfide bridge, defensins are classified into two families, the alpha-defensins (HNP) and beta-defensins (HBD). Recently two human epithelial beta defensins, HBD-1 and HBD-2 have been identified. HBD-1 has been detected in a number of normal mucosal sites, but HBD-2 is highly restricted in its expression by inflammatory stimulations. we invesigated the expression of hunam beta defensin in human male urogenital organs. METHODS: Specimens of normal human male testis, epididymis, prostate, seminal vesicles, vas deferens, urethra, bladder, ureter, kidney, pyelonephritis, epididymitis, clear renal cell carcinoma and transitional cell carcinoma of bladder were obtained as discarded material from urological surgery. Each sample was stored at snap frozen in liquid nitrogen subsequent to RNA extraction. Reverse transcription polymerase chain reaction (RT-PCR) was used to semiquantitate HBD-1 and HBD-2 mRNA using the housekeeping gene beta-actin as an internal control. Southern blotting and sequencing showed HBD-1, 2 expressions in male urogenital organs. RESULTS: We checked the expression of HBD-1, 2 mRNA in all specimen of normal human male urogenital organ, pyelonephritis, epididymitis, clear renal cell carcinoma and transitional cell carcinoma of bladder by RT-PCR and southern blotting analysis. We checked the homolgy of HBD-1, 2 by bands sequencing. CONCLUSION: Our study indicated that the normal male urogenital organs, infection and neoplasm in male urogenital organs expresses antimicrobial peptides. These may play an important role in the prevention of infections by bacterias, antimicrobial effects in infection and anticancer effects in neoplasm of male urogenital organs. These natural endogenous antibiotic peptides could be developed as novel therapeutic agents for fighting infections and neoplasms of the human male urogenital organs.