Castration Induces Down-Regulation of A-Type K+ Channel in Rat Vas Deferens Smooth Muscle.

A-type K+ channels contribute to regulating the propagation and frequency of action potentials in smooth muscle cells (SMCs). The present study (i) identified the molecular components of A-type K+ channels in rat vas deferens SMs (VDSMs) and (ii) showed the long-term, genomic effects of testosterone on their expression in VDSMs. Transcripts of the A-type K+ channel α subunit, Kv4.3L and its regulatory ß subunits, KChIP3, NCS1, and DPP6-S were predominantly expressed in rat VDSMs over the other related subtypes (Kv4.2, KChIP1, KChIP2, KChIP4, and DPP10). A-type K+ current (IA) density in VDSM cells (VDSMCs) was decreased by castration without changes in IA kinetics, and decreased IA density was compensated for by an oral treatment with 17α-methyltestosterone (MET). Correspondingly, in the VDSMs of castrated rats, Kv4.3L and KChIP3 were down-regulated at both the transcript and protein expression levels. Changes in Kv4.3L and KChIP3 expression levels were compensated for by the treatment with MET. These results suggest that testosterone level changes in testosterone disorders and growth processes control the functional expression of A-type K+ channels in VDSMCs.

Potent Hemostatic Efficacy of a Novel Recombinant Fibrin Sealant Patch (KTF-374) in Rabbit Bleeding Models.

PURPOSE: Fibrin sealants are used for hemostasis during surgery. Commercially available fibrin sealants are made of materials of human or animal origin. We developed a novel recombinant fibrin sealant patch (KTF-374) that has thin and flexible properties. This study evaluated the hemostatic efficacy of KTF-374 for various patterns of bleeding in rabbits, as compared with that of the existing fibrin-coated collagen fleece (FCCF). MATERIALS AND METHODS: Test hemostats used were KTF-374 and FCCF. Laparotomy was performed under general anesthesia in rabbits. We created wounds in the liver, caudal vena cava, and ventral aorta under anticoagulating conditions with heparin. Test hemostats were then applied to the wound site and compressed manually for 3 min. Hemostatic efficacy was evaluated with the success rate of hemostasis at 3 min. RESULTS: In all bleeding models, the success rate of hemostasis was significantly higher with KTF-374 than FCCF. The hemostatic success rate of KTF-374 and FCCF was 100% vs. 25% (p = .007) in the partial hepatectomy model (n = 8); 100% vs. 12.5% (p = .001) in the caudal vena cava resection model (n = 8); and 100% vs. 25% (p = .004) in the ventral aortic puncture model (n = 8). The wound site could clearly be recognized through the patch after the application of KTF-374 but not FCCF. CONCLUSIONS: These results suggest that KTF-374 possesses more potent hemostatic properties than FCCF for various patterns of bleeding. KTF-374 is a promising hemostat due to its potent efficacy and good visibility of the wound site through the patch.

Regulation of ryanodine receptor-mediated Ca(2+) release in vas deferens smooth muscle cells.

Ca(2+) release from intracellular store sites via the ryanodine receptor (RyR) and hormonal regulation by flutamide, an androgen-receptor (AR) antagonist, on it were examined in vas deferens (VD) smooth muscle cells (SMCs). VD and VDSMCs were obtained from two groups of male rats that were treated p.o. with 100 mg/kg flutamide (Flu) or vehicle (Vehicle). Both spontaneous and caffeine-induced Ca(2+) releases were markedly smaller in single VDSMCs from Flu than in those from Vehicle. Interestingly, [Ca(2+)](i) rise by 100 muM norepinephrine in VDSMCs from Flu was larger than that in those from Vehicle. The contractions induced by direct electrical stimulation in tissue preparations from Flu showed lower susceptibility to 30 muM ryanodine than those from Vehicle. Real-time PCR analyses revealed that the transcripts of ryanodine receptor (RyR) type 2 and type 3 (RyR2 and RyR3) were expressed in VD and markedly reduced in Flu. The protein expression of total RyR was significantly reduced by flutamide treatment, but that of inositol 1,4,5-trisphosphate receptor (IP3R) was not affected. It can be strongly suggested that long term block of AR by flutamide reduced the expression of RyR and its contribution to the contraction, but not those of IP3R in VDSMCs.

Malignancy grade-dependent expression of K+-channel subtypes in human prostate cancer.

K(+) channels are key molecules in the progression of several cancer types and considered to be potential targets for cancer therapy. We examined the gene expressions of voltage-gated (K(v)), Ca(2+)-activated (K(Ca)), and two-pore domain (K(2P)) K(+)-channel subtypes in needle-biopsy samples of human prostate cancer (PCa) by real-time PCR and compared them with those in PCa epithelial cell lines. The expression of K(v)1.3, K(Ca)1.1, K(Ca)3.1, and K(2P)1 markedly increased in the PCa group with Gleason score of 5 - 6 (GS5-6) but significantly decreased in the GS8-9 group. This malignancy grade-dependent K(+)-channel expression pattern may provide a convenient marker to understand PCa progression level.

Gender difference in BK channel expression in amygdala complex of rat brain.

The expression of large-conductance Ca(2+)-activated K(+) (BK) channel protein in amygdala complex was higher in adult (8-10 weeks old) male rats than in female. Castration at 4-6 weeks old significantly reduced BK channel expression in amygdala to the level similar to that in female. Immunocytochemical analyses of pyramidal-like neurons isolated from amygdala revealed that somas with relatively large size were highly immunoreactive to both anti-androgen receptor (AR) and anti-BK channel antibodies, while those with smaller size were not. The double-immunopositive neurons were dominant (60%) among pyramidal-like neurons isolated from amygdala of male rats but rare among those from female. The membrane current sensitive to penitrem A, a BK channel blocker, was the major K(+) current component in large neurons and showed higher current-density than that in smaller ones. These results suggest the gender-dependent cell population expressing BK channels in amygdala complex and its up-regulation by AR stimulation.