Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of caffeine on both levcromakalim-induced macroscopic and unitary currents in pig proximal urethra were investigated by the use of patch-clamp techniques (conventional whole-cell configuration and cell-attached configuration). The effects of caffeine were also examined on currents in inside-out patches of COS7 cells expressing carboxy terminus truncated inwardly rectifying K(+) channel (Kir6.2) subunits (i.e. Kir6.2DeltaC36) which form ATP-sensitive K(+) channels (K(ATP) channels). In conventional whole-cell configuration, the levcromakalim (100 microM)-induced inward current (symmetrical 140 mM K(+) conditions) was inhibited by caffeine (> or =1 mM) at a holding potential of -50 mV. In contrast, ryanodine (10 microM) caused no significant inhibitory effect on the gradual decay of the levcromakalim-induced current at -50 mV. The amplitude of the 30 microM levcromakalim-induced current was enhanced by 3-isobutyl-1-methylxanthine (IBMX, 100 microM). In cell-attached configuration, the levcromakalim-induced K(+) channel openings were inhibited by subsequent application of 10 mM caffeine, decreasing the channel open probability at -50 mV. Reverse transcriptase-polymerase chain reaction (RT - PCR) analysis revealed the presence of Kir6.2 transcript in pig urethra. Caffeine (> or =3 mM) inhibited the channel activity of Kir6.2DeltaC36 expressed in COS7 cells (3 mM caffeine, 65+/-6%, n=4; 10 mM caffeine, 29+/-2%, n=4). These results suggest that caffeine can inhibit the activity of K(ATP) channels through a direct blocking effect on the pore-forming Kir subunit.
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PMID:The effects of caffeine on ATP-sensitive K(+) channels in smooth muscle cells from pig urethra. 1101 1

1. The effects of ZD6169, a novel ATP-sensitive K(+) channel (K(ATP) channel) opener, were investigated on membrane currents in isolated myocytes using patch-clamp techniques. Tension measurement was also performed to study the effects of ZD6169 on the resting tone of pig urethral smooth muscle. 2. Levcromakalim was more potent than ZD6169 in lowering the resting urethral tone. Relaxation induced by low concentrations of ZD6169 (< or =3 microM) was completely suppressed by additional application of glibenclamide (1 microM). In contrast, glibenclamide (1-10 microM) only partially inhibited the relaxation induced by higher concentrations of ZD6169 (> or = microM). 3. Bay K8644 (1 microM) reduced the maximum relaxation produced by ZD6169 (> or =10 microM). 4. In whole-cell configuration, ZD6169 suppressed the peak amplitude of voltage-dependent Ba(2+) currents in a concentration- and voltage-dependent manner, and at 100 microM, shifted the steady-state inactivation curve of the voltage-dependent Ba(2+) currents to the left at a holding potential of -90 mV. 5. In cell-attached configuration, open probability of unitary voltage-dependent Ba(2+) channels (27 pS, 90 mM Ba(2+)) was inhibited by 100 microM ZD6169 and by 10 microM nifedipine. 6. Reverse transcriptase-polymerase chain reaction (RT - PCR) analysis revealed the presence of the transcript of the alpha(1C) subunit of L-type Ca(2+) channels in pig urethra. 7. These results demonstrate that ZD6169 causes urethral relaxation through two distinct mechanisms, activation of K(ATP) channels at lower concentrations and inhibition of voltage-dependent Ca(2+) channels at higher concentrations (about 10 microM).
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PMID:The involvement of L-type Ca(2+) channels in the relaxant effects of the ATP-sensitive K(+) channel opener ZD6169 on pig urethral smooth muscle. 1172 57

Sonic hedgehog (Shh) has been shown to be involved in the morphogenesis of many organ systems including the notochord, floor plate and limbs, as well as in the development of the left-right axis in vertebrates. Recent evidence suggests the Shh cascade plays a crucial role in the development of the foregut and hindgut. We have previously shown that prenatal exposure of fetal rats to ethylenethiourea (ETU) induces hindgut malformations and other abnormalities of the VACTERL association. The aim of this study was to determine the pattern of expression of Shh and its downstream genes during hindgut development in ETU-exposed embryos with anorectal malformations (ARMs). Pregnant Sprague-Dawley rats were mated together overnight and a positive vaginal plug was marked as gD0. On gD10, 1% ETU (125 mg/kg) was given to the experimental group and controls received the same volume of saline. Embryos were collected from both groups at gD12-16. The developing hindgut of each embryo was dissected under magnification and snap frozen. Highly purified RNA was isolated from each hindgut and first strand cDNA was prepared with appropriate negative controls. Reverse transcriptase (RT) polymerase chain reaction (PCR) was done to determine the transcripts of Shh in each sample and quantitative real-time PCR was carried out to show relative quantitative expression of Shh at each time point. Shh was detected in all samples confirming that Shh is active during the process of hindgut development in fetal rats. Relative quantitation demonstrated that Shh expression shows time-dependent changes in the developing hindgut of ETU-exposed rat embryos, and when results were compared with control samples, there was significant decrease in expression on gD14 and 15, when the cloaca normally separates into the rectum and urethra occurs in the rat fetus. The misregulated expression of Shh in the hindgut of ETU-exposed rat embryos suggests that ETU may interfere with Shh signalling. Downregulation at the time of cloacal separation into rectum and urethra indicates that Shh plays a crucial role in the development of hindgut.
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PMID:Sonic hedgehog expression in the development of hindgut in ETU-exposed fetal rats. 1636 76