摘要:

SUMMARY1. The effects of adrenoceptor agonists on venous haemodynamics were examined, utilizing the lower half perfusion method in dogs.2. Femoral arterial pressure, central venous pressure, thoracic vena caval flow, abdominal vena caval flow, renal venous flow and femoral venous flow were measured simultaneously using electronic transducers and electromagnetic flow‐meters. Hepatic volume change was monitored by the strain‐gauge arch.3. Single injections of both adrenaline (1.0 μ/kg) and isoprenaline (1.0 μg/kg) intra‐aortically produced an increase in venous return, adrenaline transiently and isoprenaline continuously.4. Epinephrine increased hepatic venous flow, while isoprenaline increased only abdominal vena caval flow.5. These findings suggest that effects of α‐adrenoceptors are more pronounced on the hepatic vein, while on other peripheral veins, effects of β‐adrenoceptors are mo

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00678.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. Levodopa, dopamine, noradrenaline and adrenaline (in increasing order of potency) depressed the tension and degree of fusion of incomplete tetanic contractions of the slow‐contracting soleus muscle in chloralose‐anaesthetized cats.2. The effects of all compounds were antagonized by propranolol (50‐20 μg/kg), but not practolol (1.0‐5.0 mg/kg). This indicates that effects are mediated by β2‐adrenoceptor stimulation.3. The effect of levodopa, but not of the catecholamines, was antagonized by prior administration of the dopa decarboxylase inhibitor benserazide. This indicates that levodopa itself is inactive, whereas its decarboxylated metabolites are active.4. The depressant action of β‐adrenoceptor agonists on incomplete tetanic contractions of the cat soleus muscle, which are exerted directly on the muscle fibres, is a model for effects exerted on slow‐contracting units of human muscles; the latter effects probably underlie the tremor observed after β‐adrenoceptor agonist administration.5. These results therefore suggest that levodopa, via its decarboxylated metabolites, dopamine, noradrenaline and adrenaline, may produce or exacerbate tremor in man. Thus in Parkinsonian patients, any centrally induced relief of tremor that levodopa may produce may be masked by tremorogenic effects of such metabolites exert

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00679.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00680.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. Guinea‐pig tracheal and lung segments were systematically examined for adrenergic nerves using the fluorescence histochemical technique. Fluorescence in nerves was enhanced with α‐methylnoradrenaline or by pretreating the animals with nialamide.2. There was a progressive decrease in density of fluorescent fibres in airway smooth muscle from the laryngeal end of the trachea, which was densely innervated, to the bronchioles, which contained only occasional fibres. This was despite obvious fluorescence in blood vessels in the lung.3. It is suggested that, if adrenergic nerves are involved in reflex bronchodilatation in this species, they directly control larger airways and other factors, e.g. non‐adrenergic inhibitory nerves, may be important in the control of smaller a

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00681.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. (±)‐Octopamine, (±)‐N‐methyl octopamine and (‐)‐α‐methyl octopamine increase the amplitude of contraction of the spontaneously beating ventricle of the molluscTapes watlingithrough action on a specific octopamine receptor.2. Unlike the excitatory responses to dopamine, noradrenaline or serotonin, the excitatory response of the ventricle to agonists at the octopamine receptor is attenuated by metoclopramide.3. Compounds with potent agonist activity at the octopamine receptor all have a single phenolic hydroxyl in the para position of the benzene ring and a β‐hydroxyl group in the phenethylamine side chain. O‐Methylation of the para phenolic group or removal of the /3‐hydroxyl group results in complete loss of agonist activity. Bulky substituents but not a single methyl group on the amino groups impair agonist activity.4. The octopamine receptor is stereo‐selective, (‐)‐octopamine is more than twenty times more active than (+)‐octopamine.5. The weak octopamine‐like activity of (‐)‐N‐methyl and a‐methyl meta octopamine indicates that the stereo‐selective receptor has a relative rather than an absolute requirement for a single phenolic hydroxyl in the para position of the benzene ring.6. These data indicate the presence of a specific, stereo‐selective receptor for octopamine in the ventricle of the molluscTapes watlingi.7. The stereo‐selectivity and structural specificity of the octopamine receptor differentiates it from receptors for dopamin

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00682.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. Sulpiride, but not procainamide, antagonizes the excitatory effects of (±)‐octopamine receptors in the Tapes ventricle. Neither compound attenuates dopamine excitation.2. Clozapine will attenuate the effects of (±)‐octopamine and (‐)‐α‐methyl octopamine at the octopamine receptor but not the excitatory effects of dopamine at dopamine receptors.3. Clozapine is more potent than its 2‐positional isomer HF 2046 in attenuating octopamine excitation. However, HF 2046, unlike clozapine, will attenuate the excitatory effects of dopamine.4. These data indicate that replacement of the 8‐chloro substituent in the clozapine nucleus with a 2‐chloro substituent decreases the ability of the compound to blockade octopamine receptors. However, the 2‐chloro‐substituted compound (HF 2046) now has the added ability to blockade excitatory dopamine receptors.5. The greater potency of clozapine than HF 2046 as an octopamine antagonist suggests that it is the 8‐chloro‐substituted aromatic ring of clozapine which overlaps the aromatic site usually occupied by th

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00683.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. The possible involvement of noradrenaline, dopamine, serotonin and 5‐hydroxyindoleacetic acid in the behavioural reinforcement produced by intravenous cocaine has been investigated.2. Rats, in Skinner boxes, were allowed to self‐administer cocaine through a chronically implanted jugular vein cannula. A consistent response rate in the order of one self‐administration every 10 min was observed with a dose of 3.0 mg/kg cocaine hydrochloride per response.3. Another group of rats was cannulated and injected with a range of one to six such doses of cocaine at 10 min intervals on the basis of the responding rate, established by rats in the Skinner box. At times of 2, 5 and 8 min after each dose of cocaine, the rats were decapitated and brain concentrations of noradrenaline, dopamine, serotonin and 5‐hydroxyindoleacetic acid were determined.4. The brain levels of noradrenaline exhibited a cyclic pattern of rise and fall after each dose of cocaine, which corresponded in its time base with the time interval between responses established by the rats in the Skin

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. The double indicator diffusion technique was used to determine pulmonary capillary permeability in rabbits of different ages. Diffusible molecules ranging in size from mannitol to inulin were used in pairs, together with a vascular tracer.2. The extraction of diffusible molecules in successive venous samples showed a rapid decline with time. The extraction at appearance time of the tracers in the venous samples was used to determine a permeability ratio for pairs of diffusible molecules.3. Pore radii and slit widths were calculated from permeability ratios by a new application of existing equations. Because the permeability ratios were similar to the ratio of the free diffusion coefficients of the diffusible molecules in all but foetal animals, the upper 95% confidence limit of the permeability ratio was used to determine the lower 95% confidence limit of pore radius in each age group. The lower limit of pore radius ranged between 7.1 nm and 25.0 nm for neonatal and older rabbits, while foetal animals showed a range of 2.7 nm to 8.3 nm.4. ThePAmfor inulin and lower limit of pore radius were used to estimate pore area and pore number per cm2capillary surface area. The pore area per cm2capillary surface area ranged between 1.58 × 10‐4cm2(neonate) to 0.45 × 10‐4cm2(adult). These values are similar to other estimates for pore area in skeletal muscle capillaries. The corresponding values for pore number were 9.99 × 107(neonate) and 0.52 × 107(adult) per cm2capillary surface area, values which are one‐tenth to one‐hundredth the estimates for pore number in skeletal muscle capillaries.5. The smaller number of large pores in the pulmonary capillaries of the adult rabbit would confer on this organ a six‐fold greater filtration‐reabsorption capacity per unit surface area, while diffusional exchange would be reduced to one‐half that seen in skeletal m

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00685.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. When isolated guinea‐pig vas deferens was pretreated with 0.01% sodium edetate in an isotonic sucrose medium and then transferred to an edetate‐free sucrose medium, the addition of CaCl2(1.1 to 35.2 mmol/1) induced a contraction.2. The contraction was greatest when the CaCl2was added soon after pretreat‐ment with edetate, and decreased with increasing time, almost disappearing after 1h.3. When KC1 (1.4 to 22.4 mmol/1) was added in place of CaCl2, the contraction was lowest soon after pretreatment with edetate, and increased with time; after 1 h, the effect was 80.7% of that observed in a preparation that had not been pretreated with ed

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00686.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARY1. Rats after a 24 h restraint developed acute gastric erosions. Cimetidine in a dose of 100 mg/kg body weight was given subcutaneously every 8 h to a group of 150 rats after restraint. A second group received saline subcutaneously (placebo group).2. Erosions in the placebo group required up to 45 days to heal (median healing time approximately 24 days). Cimetidine treatment reduced the median healing time to approximately 12 days.3. Cimetidine in this dose promotes healing of acute gastric erosions in the rat induced by restraint.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1978.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY