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Corpus Cavernosum Smooth Muscle Cells (corpus_cavernosum + smooth_muscle_cell)
Selected AbstractsSpontaneous Ca2+ Waves in Rabbit Corpus Cavernosum: Modulation by Nitric Oxide and cGMPTHE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009Gerard P. Sergeant PhD ABSTRACT Introduction., Detumescent tone and subsequent relaxation by nitric oxide (NO) are essential processes that determine the erectile state of the penis. Despite this, the mechanisms involved are incompletely understood. It is often assumed that the tone is associated with a sustained high cytosolic Ca2+ level in the corpus cavernosum smooth muscle cells, however, an alternative possibility is that oscillatory Ca2+ signals regulate tone, and erection occurs as a result of inhibition of Ca2+ oscillations by NO. Aims., The aim of this study is to determine if smooth muscle cells displayed spontaneous Ca2+ oscillations and, if so, whether these were regulated by NO. Methods., Male New Zealand white rabbits were euthanized and smooth muscle cells were isolated by enzymatic dispersal for confocal imaging of intracellular Ca2+ (using fluo-4AM) and patch clamp recording of spontaneous membrane currents. Thin tissue slices were also loaded with fluo-4AM for live imaging of Ca2+. Main Outcome Measure., Cytosolic Ca2+ was measured in isolated smooth muscle cells and tissue slices. Results., Isolated rabbit corpus cavernosum smooth muscle cells developed spontaneous Ca2+ waves that spread at a mean velocity of 65 µm/s. Dual voltage clamp/confocal recordings revealed that each of the Ca2+ waves was associated with an inward current typical of the Ca2+ -activated Cl - currents developed by these cells. The waves depended on an intact sarcoplasmic reticulum Ca2+ store, as they were blocked by cyclopiazonic acid (Calbiochem, San Diego, CA, USA) and agents that interfere with ryanodine receptors and IP3 -mediated Ca2+ release. The waves were also inhibited by an NO donor (diethylamine NO; Tocris Bioscience, Bristol, Avon, UK), 3-(5-hydroxymethyl-2-furyl)-1-benzyl indazole (YC-1) (Alexis Biochemicals, Bingham, Notts, UK), 8-bromo-cyclic guanosine mono-phosphate (Tocris), and sildenafil (Viagra, Pfizer, Sandwich, Kent, UK). Regular Ca2+ oscillations were also observed in whole tissue slices where they were clearly seen to precede contraction. This activity was also markedly inhibited by sildenafil, suggesting that it was under NO regulation. Conclusions., These results provide a new basis for understanding detumescent tone in the corpus cavernosum and its inhibition by NO. Sergeant GP, Craven M, Hollywood MA, McHale NG, and Thornbury KD. Spontaneous Ca2+ waves in rabbit corpus cavernosum: Modulation by nitric oxide and cGMP. J Sex Med **;**:**,**. [source] The Ontogenetic Expression Pattern of Type 5 Phosphodiesterase Correlates with Androgen Receptor Expression in Rat Corpora CavernosaTHE JOURNAL OF SEXUAL MEDICINE, Issue 2 2009Eleonora Carosa MD ABSTRACT Introduction., The mechanisms controlling erection in animals and in humans are mainly age-dependent. However, the ontogenesis of the biochemical machinery of erection is largely unknown. Aim., The aim of this article was to study the expression pattern of androgen receptor (AR) and the major cyclic guanosine monophosphate-hydrolyzing enzyme present in the corpora cavernosa, type 5 phosphodiesterase (PDE5), in the rat penis during development. Methods., AR and PDE5 expression was tested on ribonucleic acids (RNAs) and proteins extracted from the whole penis or from primary cultures of smooth muscle cells obtained from the corpora cavernosa of 3- (rCC3), 20- (rCC20), and 60- (rCC60) day-old rats. Rat corpus cavernosum cells were characterized by immunocytochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Main Outcome Measures., Expression of PDE5 and AR messenger RNA (mRNA) and protein have been measured by RT-PCR and Western blot, respectively. Results., A significant increase in PDE5 mRNA expression was observed with RT-PCR from prepuberty to adulthood (0.5 ± 0.06 vs. 1.6 ± 0.046 arbitrary units [a.u.]P = 0.049). This age-dependent increase was mirrored by the increase in PDE5 protein expression found when comparing neonatal to adult corpus cavernosum smooth muscle cells (1.5 ± 0.26 vs. 4.9 ± 0.59 a.u. P = 0.0038) and the further 1.6-fold increase from rCC20 to rCC60 (4.9 ± 0.59 vs. 8.0 ± 0.8 a.u. P = 0.0024). This is the first demonstration of the ontogenetic profile of PDE5 expression in corpus cavernosum smooth muscle. As it has been demonstrated that androgens control PDE5 expression and that PDE5 inhibitors need an optimal androgenic milieu to act perfectly on erection, the expression of AR protein in rat corpus cavernosum cells was then tested by Western blot. A 7.0-fold increase was observed in primary cultured cells from 3 to 60 days old (1.4 ± 0.38 vs. 9.8 ± 1.3 a.u. P = 0.0052). Conclusion., The increase in ARs during rat penile development parallels that of PDE5 RNA and protein, thus suggesting a positive effect of androgens on PDE5 expression. Carosa E, Rossi S, Giansante N, Gravina GL, Castri A, Dolci S, Botti F, Morelli A, Di Luigi L, Pepe M, Lenzi A, and Jannini EA. The ontogenetic expression pattern of type 5 phosphodiesterase correlates with androgen receptor expression in rat corpora cavernosa. J Sex Med 2009;6:388,396. [source] Expression and function of ryanodine receptors in rabbit penile corpus cavernosum smooth muscle cellsANDROLOGIA, Issue 3 2009H. G. Liu Summary This study aimed to investigate the expression and function of ryanodine receptors (RyRs) in rabbit penile corpus cavernosum smooth muscle (CCSM) cells. New Zealand white rabbit CCSM cells were cultured by primary tissue culture and identified by immunofluorescence technique. mRNA of three RyRs subunits in cultured CCSM cells was detected by reverse transcription polymerase chain reaction (RT-PCR). After excitation by noradrenaline, the concentration of Ca2+ in CCSM cells was detected by laser scanning confocal microscopy. It was found that only the RyRs1 subunit is expressed in CCSM by RT-PCR. The CCSM cells were divided into two groups: Group A, CCSM cells + 10 ,mol l,1 noradrenaline and Group B, CCSM cells + 50 ,mol l,1 procaine 10 ,mol l,1 noradrenaline. Compared with the base level and the level after noradrenaline excitation, fluorescence intensity improved 44.10 ± 6.01% in the test group A (n = 8) and 32.92 ± 4.92% (n = 8) in the procaine control group B, respectively. There were statistically significant differences between group A and group B (P < 0.01). It is concluded that RyRs1 subunit is expressed in CCSM cells and may contribute to regulating the cytoplasmic Ca2+ level. [source] | ||||||||||