Search results for "CELLULAR"

Unterschiede zwischen Tyramin und Dimethylphenylpiperazin in der Ca++-Abhängigkeit und im zeitlichen Verlauf der Noradrenalin-Freisetzung am isoliert…

1967

On the perfused rabbit heart a constant infusion of tyramine released noradrenaline continuously and independently of the external Ca++ concentration. In contrast, noradrenaline release by DMPP was only transient and required the presence of Ca++.

Der Einfluss von Acetylcholin auf den Calciumumsatz ruhender und kontrahierender Vorhofmuskulaturin vitro

1964

Acetylcholine 5 × 10−8 g/ml reduces the Ca45 uptake of the beating left atria of guinea-pig; the tissue calcium is not altered. In resting atria, acetylcholine 5 × 10−7 g/ml has no influence upon the calcium content and Ca45 uptake. It is concluded that acetylcholine acts by shortening the action potential duration and thereby reduces the release of cellular calcium per excitation.

Änderungen des Elektrolytgehaltes von Erythrozyten und Plasma bei nephrektomierten Ratten

1957

After two-stage nephrectomy in rats the potassium concentration in the red blood corpuscles (RBC) decreases from 10.6 ± 0.3 to 5.5 ± 0.3 mEq per 100 ml of RBC within 48 h. The decrease is accompanied by a much smaller increase in the plasma potassium concentration; the hyperkaliemia in nephrectomized rats is less pronounced than in nephrectomized dogs or anuric humans. Na+ in RBC increases by about 44% after nephrectomy; while there is only a very slight decrease of Na+ in plasma. Plasma chlorides drop from 10.92 ± 0.08 mEq/100 ml of plasma to 6.00 ± 0.81 mEq % within 48 h after nephrectomy. RBC chlorides tend to increase again after an initial drop from 5.22 ± 0.07 to 3.82 ± 0.90 mEq% with…

Über die Beeinflussung der Ca-Aufnahme in Lipidextrakte aus Mikrosomen und Mitochondrien des Herzens durch Digitoxin

1970

Lipids were isolated by chloroform-methanol extraction from mitochondrial and microsomal fractions of guinea-pig hearts. In the presence of digitoxin (10−9-10−6 g/ml) 15–30% more radioactive Ca was taken up by the lipid extracts than under control conditions, but the total amount of Ca in this phase remained unchanged. Thus, digitoxin produced an increase in the specific activity of the lipid-bound Ca which may be explained by an increased exchangeability of this Ca fraction. This effect of digitoxin might result in an improved availability of the lipid-bound Ca for Ca-dependent functions (e.g. contraction) of the heart muscle cell.

Ecdysteroid-dependent larval-adult oviduct transformation in the milkweed bugOncopeltus fasciatus requires absence of juvenile hormone

1987

It has been tested whether juvenile hormone plays a role in the larval-adult transformation of lateral oviducts in the milkweed bug. The transformation is ecdysteroid-dependent, as was reported previously2. Application of precocene or juvenile hormone III proved that the absence of juvenile hormone is required.

N1-methylnicotinamide improves endothelial dysfunction in human blood vessels

2012

pH-dependent hydrolysis of acetylcholine: Consequences for non-neuronal acetylcholine

2015

Acetylcholine is inactivated by acetylcholinesterase and butyrylcholinesterase and thereby its cellular signalling is stopped. One distinguishing difference between the neuronal and non-neuronal cholinergic system is the high expression level of the esterase activity within the former and a considerably lower level within the latter system. Thus, any situation which limits the activity of both esterases will affect the non-neuronal cholinergic system to a much greater extent than the neuronal one. Both esterases are pH-dependent with an optimum at pH above 7, whereas at pH values below 6 particularly the specific acetylcholinesterase is more or less inactive. Thus, acetylcholine is prevente…

Formation of N-methylnicotinamide in the brain from a dihydropyridine-type prodrug

1999

The enhancement of brain choline levels is a possible therapeutic option in neurodegenerative diseases; however, brain choline levels are held within narrow limits by homeostatic mechanisms including the rapid clearance of excess choline from the brain. The present study tests whether N-methylnicotinamide (NMN), an inhibitor of the outward transport of choline from the brain, can elevate brain choline levels in vivo. As NMN does not cross the blood-brain barrier, we synthesized and administered the brain-permeable prodrug, 1,4-dihydro-N-methyl-nicotinamide (DNMN), and tested its effect on the levels of NMN and choline in brain extracellular fluid, using the microdialysis procedure. Administ…

Effects of nitric oxide donors on cardiac contractility in wild-type and myoglobin-deficient mice

2002

1. The effects of the nitric oxide (NO) donors S-nitroso-N-acetylpenicillamine (SNAP), sodium(Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate), and (Z)-1-[N-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate) on force of contraction (F(c)) were studied in atrial and ventricular muscle strips obtained from wild-type (WT) and myoglobin-deficient (myo(-/-)) mice. 2. SNAP slightly reduced F(c) in preparations from WT mice at concentrations above 100 microM; this effect was more pronounced in myo(-/-) mice. 3. DEA-NONOate reduced F(c) in preparations from myo(-/-) mice to a larger extent than those from WT mice. 4. DETA-NONOate reduced F(c) in preparations…

Zur Frage der Beziehungen zwischen enddiastolischem Ventrikeldruck unddp/dt bzw.d 2 p/dt 2 der Ventrikeldruckkurve des Herzens

1969

Correlations between left ventricular enddiastolic pressure of the heart and first and second derivation of left ventricular pressure curve (dp/dt, d2p/dt2 respectively) were examined at various hemodynamic conditions. The results showed only a particular dependence ofdp/dt andd2p/dt2 from enddiastolic pressure. Therefore, it is concluded, that enddiastolic pressure is not the most important factor, which influences the dynamics of ventricular contraction.