Search results for "Acellular"
showing 10 items of 1986 documents
Effect of Divalent Cations on the Contractile Response of Rat Aorta to Depolarization before and after Nifedipine Treatment
1996
The influence of the divalent cations, Ca2+, Mg2+ and Ba2+, on the contractile response of the rat aorta to KCl and on the recovery of this response after nifedipine treatment was analyzed. KCl (80 mmol/l) promoted a two-phase (phasic and tonic) contractile response in Krebs solution but, as expected, no contractile response in Ca(2+)-free medium. In Mg(2+)-free medium, the phasic response to KCl was unaffected but the tonic one decreased slowly, suggesting that a long incubation time in the absence of Mg2+ (65 min) promotes a loss of or a change in the intracellular distribution of this ion that modifies Ca2+ entry through L channels or Ca2+ handling. Ba2+ (1.8 mmol/l) contracted the rat a…
Murine tissue factor disulfide mutation causes a bleeding phenotype with sex specific organ pathology and lethality.
2019
Tissue factor is highly expressed in sub-endothelial tissue. The extracellular allosteric disulfide bond Cys186-Cys209 of human tissue factor shows high evolutionary conservation and in vitro evidence suggests that it significantly contributes to tissue factor procoagulant activity. To investigate the role of this allosteric disulfide bond in vivo, we generated a C213G mutant tissue factor mouse by replacing Cys213 of the corresponding disulfide Cys190-Cys213 in murine tissue factor. A bleeding phenotype was prominent in homozygous C213G tissue factor mice. Pre-natal lethality of 1/3rd of homozygous offspring was observed between E9.5 and E14.5 associated with placental hemorrhages. After b…
Mechanism of Block by 4-Aminopyridine of the Transient Outward Current in Rat Ventricular Cardiomyocytes
1998
The effects of 4-aminopyridine (4-AP) on the transient outward current (I to ) were investigated in rat ventricular cardiomyocytes at different values of intracellular pH (pH i ) and extracellular pH (pH o ). The 4-AP was administered either extracellularly (bath application) or intracellularly (diffusion from the intrapipette solution). The 4-AP diminished I to given either from inside or outside the cell membrane. The block by extracellularly applied 4-AP (4-AP o ) of the peak amplitude of I to was decreased by external acidification but increased by external alkalinization: conversely. the block by 4-AP o was decreased by internal alkalinization but increased by internal acidification. I…
Exercise and recovery in frog muscle: metabolism of PCr, adenine nucleotides, and related compounds
1996
The effects of exercise (swimming), fatigue, and recovery on the intracellular pH (pHi), energy-rich phosphates, and related metabolites were studied in the gastrocnemius muscle of common frogs (Rana temporaria) at 20 degrees C. Exercise caused a rapid decrease in the content of phosphocreatine (PCr) and a corresponding increase in that of Pi. The ATP level remained virtually constant for 1 min; its precipitous decrease during the following minute was associated with a rise in the contents of inosine 5'-monophosphate (IMP) and NH4+, indicating a marked activation of AMP deaminase. Five minutes of swimming caused severe fatigue, which was correlated with decreases in muscle PCr (-85%), ATP …
Evaluation by reverse phase HPLC of [3H]acetylcholine release evoked from the myenteric plexus of the rat.
1990
Myenteric plexus-longitudinal muscle strips isolated from the small intestine of rats were incubated with [3H]choline to measure the synthesis and the release of [3H]acetylcholine. To separate different radioactive compounds (acetylcholine, choline, phosphorylcholine) from both the tissue and the overflow a new method, the reverse phase HPLC, was used. The radiochromatogram following the injection of a [3H]choline-standard and a [14C]acetylcholine-standard onto the HPLC showed a clear separation of both isotopes with a recovery rate of roughly 100%. Incubation of the muscle strips with [3H]choline caused the synthesis of [3H]acetylcholine (30,000 dpm/preparation) that increased 2-fold, when…
Long-term expression of differentiated functions in hepatocytes cultured in three-dimensional collagen matrix.
1998
Hepatocytes entrapped in collagen gel and cultured in serum-free conditions survived longer than cells cultured on plastic (5 days vs. 3 weeks), showed fewer signs of early cell senescence (no increase in c-fos oncoprotein expression), and maintained the expression of differentiated hepatic metabolic functions over a longer period of time. Cells cultured in collagen gels retained their ability to respond to hormones. The insulin-stimulated glycogen synthesis rate remained fairly constant during 18 days in culture (between 5.4 +/- 0.37 and 9 +/- 2.7 nmol glucose/h/microg DNA). Collagen-cultured hepatocytes recovered glycogen stores to levels similar to those found in liver, or in hepatocytes…
Muscle protein synthesis, mTORC1/MAPK/Hippo signaling, and capillary density are altered by blocking of myostatin and activins
2012
Loss of muscle mass and function occurs in various diseases. Myostatin blocking can attenuate muscle loss, but downstream signaling is not well known. Therefore, to elucidate associated signaling pathways, we used the soluble activin receptor IIb (sActRIIB-Fc) to block myostatin and activins in mice. Within 2 wk, the treatment rapidly increased muscle size as expected but decreased capillary density per area. sActRIIB-Fc increased muscle protein synthesis 1–2 days after the treatment correlating with enhanced mTORC1 signaling (phosphorylated rpS6 and S6K1, r = 0.8). Concurrently, increased REDD1 and eIF2Bε protein contents and phosphorylation of 4E-BP1 and AMPK was observed. In contrast, pr…
Detection of flap venous and arterial occlusion using interstitial glucose monitoring in a rodent model.
2010
Background: Free tissue transfer necessitates vigilant postoperative monitoring for vessel occlusion. Unfortunately, most monitoring methods require experienced personnel and are expensive to use. Furthermore, many tests have low sensitivity, low specificity, or significant delay between vessel occlusion and detection. The authors report on a novel method of tissue monitoring that avoids these limitations by tracking interstitial glucose concentration. Methods: Vertical rectus abdominis myocutaneous flaps were elevated in adult rats based on the superior epigastric vessels. Interstitial glucose within the flaps was monitored using a transcutaneous sensor. Interstitial glucose was recorded f…
Evidence that depletion of internal calcium stores sensitive to noradrenaline elicits a contractile response dependent on extracellular calcium in ra…
1993
1. Noradrenaline 1 microM induced a contractile response in rat isolated aorta in the presence or in the absence of extracellular Ca2+ with depletion of intracellular Ca2+ stores. Thereafter, during incubation in the presence of Ca2+, an increase in the resting tone was observed. Such a contractile response did not occur after exposure to caffeine or 5-hydroxytryptamine. 2. This increase in tension was inhibited in a concentration-dependent manner by alpha-adrenoceptor antagonists (prazosin, phentolamine and yohimbine), the non-specific relaxing compound, papaverine and by the Ca(2+)-entry blocker, nifedipine. Therefore, this contractile process is related to depletion of Ca2+ stores sensit…
Nitric oxide, via activation of guanylyl cyclase, suppresses alpha2-adrenoceptor-mediated 5-hydroxytryptamine release from neuroendocrine epithelial …
1998
Isolated tracheae of newborn rabbits were incubated in vitro and the outflow of 5-hydroxytryptamine (5-HT) was determined by HPLC with electrochemical detection. Evidence has previously been provided that this 5-HT outflow derives from neuroendocrine epithelial (NEE) cells of the airway mucosa. Phenylephrine, at a maximally effective concentration of 10 microM, caused a transient increase in 5-HT outflow by about 250%, an effect mediated by alpha2B-adrenoceptors, as previously shown. The phenylephrine-induced 5-HT release remained unchanged in calcium-free medium, but was reduced by 75% when the tracheae were incubated in calcium-free medium which contained 0.5 mM EDTA, a treatment known to…