摘要:

The ability of tetrodotoxin and verapamil to block Ca++-dependent action potentials (CaP) produced in superfused, canine cardiac Purkinje fibers was studied using intracellular microelectrodes. CaP were produced in fibers superfused with a Na+-free (substituted by tetraethylammonium chloride) high Ca++ (16.2 mM) Tyrode’s solution (pH 7.4 or pH 6.0). In 30 fibers studied two populations of resting membrane potentials (RMP) were observed. In one, the mean RMP was –43 ± (SE) 3 mV, in the second it was -63 ± 2 mV. The high RMP was seen at pH 7.4, while the low RMP was observed at pH 6.0. It was possible to block low pH, CaP with verapamil alone, while high RMP, high pH, CaP could be totally blocked only with a combination of verapamil plus tetrodo

ISSN:0031-7012    

DOI:10.1159/000137869

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

UM-272 (NN-dimethylpropranolol), a quaternary antiarrhythmic agent, was administered sublingually to dogs with ouabain-induced ventricular tachycardias. Both antiarrhythmic efficacy and bioavailability were compared to oral drug. Sublingual UM-272 converted ventricular tachycardia to sinus rhythm in all 5 dogs. The area under the plasma concentration time curve at 90 min was 4–12 times greater than for oral drug, suggesting the existence of an absorption-limiting process in the intestine, and providing an alternate form of administration for quaternary drug

ISSN:0031-7012    

DOI:10.1159/000137870

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effects of naloxone, pentobarbitone, or their combination, on arterial blood gases were studied in urethane-anaesthetised rats. Naloxone itself did not significantly alter the blood gases. Pentobarbitone significantly decreased PO2 and elevated PCO2, and these effects were prevented by pretreatment with naloxone. Arterial blood pH was unaffected by any of the drugs. The findings suggest that naloxone lacks a specific analeptic effect, but can antagonise respiratory depression induced by pentobarbitone.

ISSN:0031-7012    

DOI:10.1159/000137871

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effect of a new beta-adrenoceptor agonist, ICI 118,587, on the blood levels of cyclic AMP, glucose, lactate, and FFA was studied in conscious rats. ICI 118,587 (200 μg/100 g s.c.) increased the cyclic AMP level in the normal and reserpine-pretreated rat, and increased the FFA level in the reserpine-pretreated rat. Adrenaline (10μg/100g s.c.) increased the levels of cyclic AMP, glucose, and lactate in the normal rat, and increased the FFA level in the reserpine-pretreated rat. The increases in these metabolites induced by this particular dose of adrenaline were inhibited by ICI 118,587. In the normal or reserpine-pretreated rat, ICI 118,587 acts as a beta-agonist on metabolism, and is capable of antagonizing the metabolic effects of adrenalin

ISSN:0031-7012    

DOI:10.1159/000137872

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Activation of adenylate cyclase (AC) by PGE2, histamine and gastrointestinal hormones was studied in parietal cell-free gastric biopsy specimens from the corpus of patients with proven high gastrin achlorhydria. PGE2, somatostatinVIP, pentagastrin and secretin activated AC in a concentration-dependent manner both in normal and in atrophic mucosa. Histamine activated AC only in normal gastric mucosa, being entirely ineffective in mucosa devoid of parietal cells. The results indicate that histamine-sensitive AC disappears in patients with achlorhydria, probably due to their loss of parietal cells. Enzyme activity in response to somatostatin, VIP, pentagastrin, secretin and PGE2 remains unchanged in these patients indicating AC localization in nonparietal cells, e.g. chief or mucous cells.

ISSN:0031-7012    

DOI:10.1159/000137873

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Niacin at concentrations of 0.1–10 mM resulted in a dose-dependent reduction of oxygen toxicity in a mouse alveolar macrophage model. These concentrations of niacin did not affect alveolar macrophage function under normoxic conditions. Our results are consistent with observations from other groups that niacin reduces oxygen toxicity in bacteria and paraquat toxicity in bacteria and rats. The mechanism by which niacin reduces oxygen toxicity may involve the ability of niacin to function as an alternate substrate for NAD synthesis. Niacin may have clinical value in the prevention of oxygen toxicit

ISSN:0031-7012    

DOI:10.1159/000137874

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Δ9-Tetrahydrocannabinol (THC) markedly potentiated barbital Na sleeping time in mice and rats. The magnitude and duration of this effect were markedly enhanced when the animals were pretreated with SKF 525-A, a nonspecific inhibitor of liver microsomal enzymes responsible for drug metabolism. Moreover, depending on the method and species of animal used, THC was found to be one half (mouse hot plate), one third (mouse tail flick), and one eighth (rat tail flick) as potent an analgesic as morphine SO4. However, pretreatment with SKF 525-A significantly potentiated the analgesic activity in mice. These data suggest that intact THC and not necessarily a metabolite(s) is principally responsible for the CNS depressant and analgesic effects observed

ISSN:0031-7012    

DOI:10.1159/000137875

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

N-trimethyl-acetyl-4-aminobutyric acid, called PG2, is a new anticonvulsant acting as a 4-aminobutyric acid (GABA) pro-drug. The stimulatory effect of PG2 on synaptosomal 14C-GABA release and its inhibitory effect of synaptosomal 14C-GABA uptake were studied together with its pharmacokinetics after intracardiac and oral administration to rat. PG2 is a weak inhibitor of the GABAse system in vitro with an apparent Ki value of 0.83 mmol/l.

ISSN:0031-7012    

DOI:10.1159/000137876

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effect of propoxyphene on the elimination kinetics of antipyrine was examined in New Zealand white rabbits. Serum concentrations of antipyrine were measured by high-performance liquid chromatography (HPLC). No significant alterations in the elimination half-life, apparent volume of distribution or total plasma clearance of antipyrine were observed with propoxyphene pretreatment. These results are in contrast to the reported impaired clearance of antipyrine by propoxyphene in man.

ISSN:0031-7012    

DOI:10.1159/000137877

出版商:S. Karger AG    

年代:1983

数据来源: Karger