Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor. Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase. It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.
 ...
PMID:Suppression and stimulation mechanisms controlling glucagon secretion in a case of islet-cell tumor producing glucagon, insulin, and gastrin. 0 26

The mechanism of action of adiphenine on in vitro rat anterior pituitary TSH release was compared to that of the physiological stimulator TRH. The comparative study showed that adiphenine and TRH were able to increase TSH release in a dose-dependent manner, had similar time courses of action for equipotent stimulating concentrations and produced similar aspects of stimulated TSH cells. However, there were several differences between the effects of adiphenine and TRH. Adiphenine action was inhibited by 20 mM K+; was not calcium dependent; was inhibited by neither thyroid hormones nor somatostatin; was little affected by energy depression. It is concluded that adiphenine probably acts near the ultimate steps of the TSH release pathway and could be a useful pharmacological tool for studying the mechanism of TSH release.
 ...
PMID:Comparison of adiphenine and TRH effects on TSH release by rat pituitary in vitro. 1 85

Neuron cell bodies of Helix pomatia were voltage-clamped with a 300-millisecond depolarizing test pulse (pulse II) delivered I second after a depolarizing conditioning pulse (pulse I). The outward current, measured 200 milliseconds after the onset of pulse. II, exhibited a strong depression that was dependent on the presence of pulse. I. The maximum depression of the pulse II outward current occurred when pulse I voltages lay in the range over which calcium influx is inferred to be greatest; depression of the pulse II current subsided as pulse I potentials approached the putative calcium equilibrium potential. In the presence of extracellular [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA) or D600, the intensity of the pulse II current became largely independent of pulse I, approaching the values of maximal depression seen in normal Ringer solution. On the other hand, lowering the intracellular pH with extracellular carbon dioxide-carbonate buffer had no measurable effect on the outward currents. Other experiments showed that it is primarily the calcium-dependent, outward-current hump of the N-shaped late current-voltage curve that is depressed by presentation of the conditioning pulse. It was concluded that distinct from an early potassium-activating role, calcium entering during a depolarization leads, during a subsequent depolarization, to a depression of the calcium-activated potassium system that persists for many seconds.
 ...
PMID:Calcium-dependent depression of a late outward current in snail neurons. 1 21

The effect of changing extracellular pH (pHe) on the spontaneous activity of neurons in brain slices taken from the ventral layer of the rat medulla oblongata was compared to the response of neurons in dorsal slices. In the ventral medulla, more than 50% of the neurons were excited by H+. These neurons were found just lateral to the pyramidal tract between the root of the hypoglossal nerve and the trapezoid body. In the dorsal medulla, low pHe caused an inhibition of activity in most neurons, although a few were excited. The fact that H+ elicted excitation predominantly in the ventral medullary substrate to respond to pHe changes. Depression of synaptic transmission within the neuronal network in the slice by reducing the [Ca2+]e and increasing the [Mg2+]e altered the nature of responses of neurons to H+: In the ventral medulla, the majority of neurons were inhibited by H+, whereas in the dorsal medulla more than 50% of neurons were excited. Therefore, "specificity" of the ventral medullary neurons seemed to be dependent upon intact synaptic connections. A possible role of acetylcholine-acetylcholinesterase system in the response of ventral medullary neurons to H+ is discussed.
 ...
PMID:Effect of H+ on spontaneous neuronal activity in the surface layer of the rat medulla oblongata in vitro. 2 40

Treatment of chronic uremia by hemodiafiltration requires replacement of the filtrate. Using Ringer's solution alone, there is a depression of pH because of bicarbonate loss. To bring the acid base status back to normal, sodium lactate in increasing concentrations (283 mg% = 32 mM/1, 361 mg% = 40 mM/1; 462 mg% = 51 mM/1; 508 mg% = 57 mM/1) was added to the replacement fluid. The optimal concentration is 450 mg% (=50 mM/1) sodium lactate, provided the following conditions are fulfilled: (a) substitution after the filter; (b) mixing ratio of blood and substitution fluid 1:2. Using 12-15 liters of substitution fluid during a 5 hr treatment, the added lactate amounts to 60 g (=0.54 M). With continuous addition of lactate, the serum concentration of lactate is 3.5 times normal and the concentration of serum pyruvate 4 times normal. An excess lactate concentration, according to Huckabee [1,2], was thus not observed. The sieving coefficients were the following: sodium, potassium, urea, lactate, pyruvate, and phosphate 1; chloride greater then 1; calcium and protein less than 1. Serum osmolality fell, on the average, 9 mOsmol/1 during diafiltration.
 ...
PMID:Acid base status during treatment of chronic uremia with diafiltration. 2 47

The influence of mainly alpha-adrenergic drugs (noradrenaline, adrenaline, phenylephrine), indirect sympathomimetics (ephedrine, tyramin) and dopamine on the exocrine pancreatic function of the isolated perfused organ of cats was studied. The injection of noradrenaline and adrenaline induced simultaneously a rapid depression of flow rate and an increase of perfusion pressure. Phenylephrine, indirect sympathomimetic drugs and dopamine did not change the perfusion pressure and the hydrelatic function (flow rate, secretion of chloride and total calcium). The protein and enzyme secretion was enhanced both in normal animals and cats pretreated by reserpine or 6-hydroxydopamine. The pancreatic protein secretion was inhibited by alpha-adrenolytic as well as beta-adrenolytic substances, tetracain and atropine. It is concluded, that mainly alpha-adrenergic drugs stimulate the pancreatic enzyme secretion in a cholinergic manner.
 ...
PMID:[The effect of mainly alpha-adrenergic drugs, indirect sympathomimetrics and dopamine on exocrine pancreatic function. Studies in the isolated cat pancreas (author's transl)]. 2 65

1. The effects of decreasing pH from 7.40 to 6.20 on the tension developed by direct activation of the myofilaments and by Ca2+ release from the sarcoplasmic reticulum were studied comparatively in segments of single cells of skeletal muscle (frog semitendinosus) and cardiac muscle (rat ventricle) from which the sarcolemma had been removed by micro-dissection (skinned muscle cells). 2. The concentration of free Ca2+ in the solutions was buffered with ethylene glycol-bis (beta-aminoethylether N,N'-tetraacetic acid (EGTA). The change of the buffer capacity of a given [total EGTA] caused by varying pH and the uncertainty about the value of the equilibrium constant for Ca-EGTA have been taken into account in the interpretation of the results. 3. Decreasing pH from 7.40 to 6.20 produced an increase in the [free Ca2+] required for the myofilaments to develop 50% of the maximum tension by a factor of about 5 in skinned cardiac cells but of only 3 in skeletal muscle fibres. In addition, acidosis depressed the maximum tension developed in the presence of a saturating [free Ca2+] by approximately the same amount in the two tissues. 4. The pH optimum for loading the sarcoplasmic reticulum of skinned fibres from skeletal muscle decreased when the pCa (-log [free Ca2+]) in the loading solution decreased. The optimum was pH 7.40-7.00 for a loading at pCa 7.75, pH 7.00-6.60 at pCa 7.00 and pH 6.60-6.20 at pCa 6.00. 5. The pH optimum for loading the sarcoplasmic reticulum of skinned cardiac cells with a solution at pCa 7.75 was about pH 7.40 as in skeletal muscle fibres. But the cardiac sarcoplasmic reticulum could not be loaded with a [free Ca2+] much higher than pCa 7.75 because a higher [free Ca2+] triggered a Ca2+-induced release of Ca2+ from the sarcoplasmic reticulum. 6. The pH optimum of about 7.40 for the loading of the cardiac sarcoplasmic reticulum was also optimum for the Ca2+-induced release of Ca2+ from it. 7. It was concluded that the effects of acidosis on the cardiac sarcoplasmic reticulum accentuate the depressive action of decreasing pH on the myofilaments. This may explain the pronounced depression of contractility observed during acidosis in cardiac muscle. In contrast, a moderate acidosis causes an effect on skeletal muscle sarcoplasmic reticulum that could compensate for the depressive action on the myofilaments, which is, in addition, less pronounced than in cardiac muscle.
 ...
PMID:Effects of pH on the myofilaments and the sarcoplasmic reticulum of skinned cells from cardiace and skeletal muscles. 2 57

1 The effect of Ba2+ on the synchronous release of acetylcholine from frog motor nerve terminals was studied by conventional electrophysiological techniques. 2 When Ca2+ and Ba2+ were the only divalent cations in the bathing fluid, Ba2+ caused a presynaptic reduction in the amplitude of the endplate potential (e.p.p.). This effect was surmountable by increasing the Ca2+ concentration. 3 The affinity constant (KA) for Ba2+, calculated on the assumption that Ba2+ is a competitive inhibitor of the agonist, Ca2+, was 1.1 +/- 0.4 mM-1 (mean +/- s.e. mean, n = 8). 4 When e.p.ps were depressed by the addition of 1 mM Mg2+, addition of Ba2+ (1 to 3 mM) caused either a further presynaptic depression of moderate magnitude or had no additional effect. 5 When e.p.p.s were depressed with [Mg2+] greater than or equal to 2 mM, addition of Ba2+ greater than or equal to 0.9 mM enhanced the e.p.p. amplitude by a presynaptic mechanism. 6 The interaction of the divalent cation antagonists Mg2+ and Ba2+ with the agonist, Ca2+ is discussed. It is demonstrated that a model which considers the nonequilibrium, kinetic properties of binding can be used to describe interactions between divalent cations at the external surface of the motor nerve ending.
 ...
PMID:Enhancement by an antagonist of transmitter release from frog motor nerve terminals. 2 81

The direct and indirect actions on left ventricular dynamics of contrast material (sodium meglumine diatrizoate) currently used for coronary arteriography, modified ionic material (sodium meglumine calcium metrizoate) and non-ionic material (metrizamide) were assessed in conscious and anesthetized dogs. In both anesthetized and conscious animals, the diatrizoate compound caused an early (3--10 sec after injection) decrease in peak dp/dt and dp/dt/LVP40, followed by late (10--20 sec after injection) increases in these variables. The predominant early and later effects of the calcium metrizoate compound were increases in parameters of LV contractile state. Metrizamide produced no significant early alterations, but later induced a small increase in these variables. The positive inotropic actions of each of the contrast materials were attenuated by beta adrenergic blockade. The early effects of the contrast materials were similar in the presence of segmental ischemia. The late positive inotropic effects in response to the diatrizoate compound and metrizamide were not observed in the ischemic state, while the positive inotropic response induced by the calcium metrizoate compound was significantly reduced. Thus intracoronary administration of sodium meglumine diatrizoate produced direct myocardial depression, followed by adrenergically mediated myocardial stimulation. Calcium metrizoate caused prominent direct and adrenergically mediated augmentation in contractile state. Metrizamide induced the least alteration in LV contractile state.
 ...
PMID:Direct and reflex myocardial effects of intracoronary administered contrast materials in the anesthetized and conscious dog: comparison of standard and newer contrast materials. 3 Jul 33

The competitive reversible beta-adrenoceptor antagonist activity of Ro 03-5255 [1-(5-acetylaminobenzfuran-2-yl)-2-isopropylaminoethanol] upon isoprenaline-induced increases of the rate and tension of guinea-pig isolated atria is described. The chlorinated derivative [Ro 03-7894; 1-[5-chloracetylaminobenzfuran-2-yl)-2-isopropyl-aminoethanol] in contrast exhibited concentration-dependent non-competitive irreversible blocking activity as measured by depression of the maximum responses which were not restored by a washout period that successfully reversed Ro 03-5255. When orciprenaline was used as a weak agonist of low efficacy, the maximum responses were depressed to a greater extent. The blockade by Ro 03-7894 was relatively specific for beta-adrenoceptors since it did not antagonize histamine or calcium chloride. The depression of the maximum responses to orciprenaline was reduced by the presence of sodium thiosulphate. Sodium thiosulphate was ineffective in reversing an established blockade. The blockade by Ro 03-7894 was therefore assumed to involve irreversible binding to the beta-adrenoceptor after conversion to an appropriate electrophilic ligand. The significance of this is discussed.
 ...
PMID:Irreversible beta-adrenoceptor blockade of atrial rate and tension responses. 3 50


1 2 3 4 5 6 7 8 9 10 Next >>