Tetrahydrobiopterin prevents chronic ischemia-related lower urinary tract dysfunction through the maintenance of nitric oxide bioavailability

This study aimed to investigate the influence of chronic ischemia on nitric oxide biosynthesis in the bladder and the effect of administering tetrahydrobiopterin (BH4), a cofactor for endothelial nitric oxide synthase (eNOS), on chronic ischemia-related lower urinary tract dysfunction (LUTD). This study divided male Sprague–Dawley rats into Control, chronic bladder ischemia (CBI) and CBI with oral BH4 supplementation (CBI/BH4) groups. In the CBI group, bladder capacity and bladder muscle strip contractility were significantly lower, and arterial wall was significantly thicker than in Controls. Significant improvements were seen in bladder capacity, muscle strip contractility and arterial wall thickening in the CBI/BH4 group as compared with the CBI group. Western blot analysis of bladder showed expressions of eNOS (p = 0.043), HIF-1α (p < 0.01) and dihydrofolate reductase (DHFR) (p < 0.01), which could regenerate BH4, were significantly higher in the CBI group than in Controls. In the CBI/BH4 group, HIF-1α (p = 0.012) and DHFR expressions (p = 0.018) were significantly decreased compared with the CBI group. Our results suggest that chronic ischemia increases eNOS and DHFR in the bladder to prevent atherosclerosis progression. However, DHFR could not synthesize sufficient BH4 relative to the increased eNOS, resulting in LUTD. BH4 supplementation protects lower urinary tract function by promoting eNOS activity.

Axillary Reconstruction Using a Pedicled Thoracodorsal Artery Perforator Flap Including Latissimus Dorsi Muscle Strip

For axillary reconstruction, most reconstructive surgeons use the latissimus dorsi flap because of its usefulness and reliability. However, the latissimus dorsi musculocutaneous flap poses complications such as donor site morbidity and poor aesthetic results. Moreover, the thoracodorsal artery perforator (TDAP) flap, without muscle, presents difficulties for the delicate procedure of dissecting the perforators separately. Therefore, we propose the use of a pedicled TDAP flap including a latissimus dorsi muscle strip for axillary reconstruction, as it is believed to be easier and safer to perform.

Amphibian toxins from the skin of Bufo regularis have inhibitory effect on electrically invoked contractile response and bimodal effects on tone of longitudinal muscle of guinea pig ileum

The skins of some amphibians contain potentially bioactive principles that may have pharmaceutical, medicinal, toxicological or chemical importance. In addition, such active principles can be used as tools in biomedical research. The present study aims at isolating and purifying bioactive principles from the skin of Bufo regularis and studying their effect on isolated longitudinal smooth muscle strip of guinea pig ileum. High performance liquid chromatography (HPLC) was used to isolate toad toxins. The effects of crude, semi-purified and purified extracts were tested on longitudinal smooth muscle of guinea pig ileum using organ bath method. Effect of the toxins was studied on electrically-induced contractile response and the basal tone of the longitudinal muscle strip. HPLC purification resulted in four different bioactive components with a λmax UV absorbance pattern of around 295 nm. When tested on guinea pig ileum they had persistent inhibitory effect on the electrically-induced contractile responses. The pattern of effect was initial excitatory followed by long lasting inhibitory effect on tone of longitudinal muscle. The HPLC eluate at 79th min in methanol preparative run corresponding to the eluate at 40th min in the acetonitrile run had the maximum bioactivity. Hence, it was concluded that the skin of B. regularis contains four different components which vary in their potency on isolated smooth muscle strip of guinea pig ileum.Keywords: Bufo regularis, organ bath, longitudinal muscle of ileum, toad toxin, electrical field stimulation

Effect ofAurantii Fructus Immaturus Flavonoidon the Contraction of Isolated Gastric Smooth Muscle Strips in Rats

This study was designed to investigate the effect ofAurantii fructus immaturus flavonoid(AFIF) on the contraction of isolated gastric smooth muscle in rats and explore its underlying mechanisms. Isolated antral longitudinal smooth muscle strip (ALSMS) and pyloric circular smooth muscle strip (PCSMS) of rats were suspended in tissue chambers. The responses of ALSMS and PCSMS to administration of AFIF were observed. Cyclic guanosine monophosphate (cGMP) and protein kinase G (PKG) levels of PCSMS were measured by ELISA kits. In this study, AFIF showed no significant effect on ALSMS contraction, but it dose-dependently reduced the mean contraction amplitude of PCSMS. When the concentration of AFIF reached 3000 μg/mL, 6000 μg/mL, and 10000 μg/mL, its inhibitory effect on PCSMS contraction was significant. This effect of AFIF was weakened in Ca2+-rich environment. And Nω-nitro-L-arginine methyl (L-NAME), the inhibitor of nitric oxide synthase (NOS), significantly inhibited AFIF’s action in comparison with control (P<0.05). After incubation with AFIF for 30 min, levels of cGMP and PKG in PCSMS were significantly increased compared with control (P<0.05). Our results suggest that AFIF has a dose-dependent diastolic effect on PCSMS in rats, which may be related to the regulatory pathway of NO/cGMP/PKG/Ca2+.

Molecular, cellular, and muscle strip mechanics of the mdx mouse diaphragm

Duchenne muscular dystrophy (DMD) is a lethal disorder caused by defects in the dystrophin gene, which leads to respiratory or cardiac muscle failure. Lack of dystrophin predisposes the muscle cell sarcolemmal membrane to mechanical damage. However, the role of myosin in this muscle weakness has been poorly addressed. In the current study, in addition to measuring the velocity of actin filament propulsion (υmax) of mdx myosin molecules purified from 3- and 12-mo-old control (C57Bl/10) and mdx (C57Bl/10 mdx) mouse diaphragms, we also measured myosin force production. Furthermore, we measured cellular and muscle strip force production at three mo of age. Stress (force/cross-sectional area) was smaller for mdx than control at the muscle strip level but was not different at the single fiber level. υmax of mdx myosin was not different from control at either 3 or 12 mo nor was their relative myosin force. The type I and IIb myosin heavy chain composition was not different between control and mdx diaphragms at 3 or 12 mo. These results suggest that the myosin function, as well as the single fiber mechanics, do not underlie the weakness of the mdx diaphragm. This weakness was only observed at the level of the intact muscle bundle and could not be narrowed down to a specific mechanical impairment of its individual fibers or myosin molecules.