摘要:

The pithed guinea pig is introduced as a model for evaluating positive inotropic and vasodilator effects of substances. The model was characterized by means of ouabain, isoprenaline and hydralazine. In this model, the effects of some new noncatecholamine, nonglycoside positive inotropic agents were compared with respect to an increase in LV-dp/dtmax, effects on heart rate and vasodilator effects. Comparing equieffective doses (inducing an increase in LV-dp/dtmax AR-L 100.

ISSN:0031-7012    

DOI:10.1159/000138091

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Lysophosphatidylcholine (LPC) had recently been shown to accumulate in the ischemic heart and was demonstrated to be arrhythmogenic in perfused hearts. The present study was designed to examine the effects of calcium and verapamil on LPC-induced arrhythmias. Rat hearts were perfused through the aorta with oxygenated Krebs-Henseleit buffer at 37°C. The occurrence of ventricular fibrillation was dependent on the LPC concentration and perfusion time. In subsequent experiments, each heart was perfused with a buffer containing 20 μM LPC for 3 min and was followed with a 10 min washout period. Ventricular fibrillation occurred in all 8 control experiments. When the Ca2+ concentration was reduced to half, only 3 out of 8 hearts fibrillated. In the presence of 0.2 mg/l of verapamil, 7 out of 9 hearts fibrillated, and the time to fibrillation was not increased significantly by verapamil. These results suggest that calcium may be important in LPC-induced arrhythmias, and this effect is not significantly attenuated by the Ca2+ antagonist, verapami

ISSN:0031-7012    

DOI:10.1159/000138092

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The arcuate nucleus (AN) is the presumed origin of the dopaminergic innervation of posterior lobe of the pituitary. Posterior lobe dopamine levels were determined in rats that had been neonatally treated with monosodium glutamate (MSG) to lesion the AN. MSG-induced AN damage was confirmed neurochemically, histologically and immunocytochemically. MSG treatment resulted in a substantial loss of AN neurons and approximately a 50% loss of dopamine uptake capacity (Vmax) in the mediobasal hypothalamus. Posterior pituitary dopamine levels were not significantly altered by MSG-induced AN damage. These results suggest that MSG treatment spares the tuberohypophyseal dopamine system and that the AN may not be the sole origin of the dopaminergic innervation of the posterior pituitary.

ISSN:0031-7012    

DOI:10.1159/000138093

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The relationship between extracellular calcium and urinary bladder function was investigated by studying the effect of the specific calcium antagonist diltiazem on the functional ability of the in vitro whole rabbit urinary bladder to empty in response to pharmacological stimulation. The bladder was found to require an extracellular calcium concentration of 4.5 × 10–4M to elicit near complete cholinergic-mediated emptying. Diltiazem (1 × 10–6–1 × 10–4M) inhibition of bladder function was competitively antagonized by increasing the extracellular calcium concentration (0.45 × 10–4–3.6 × 10–4M). In the absence of diltiazem, alterations in the extracellular calcium concentration between 0.45 × 10–4 and 3.6 × 10–4M had no significant effects on bladder

ISSN:0031-7012    

DOI:10.1159/000138094

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The effects of 1-iodo-3-aminomethyl-5,6,7,8-tetrahydro-2-naphthol (ONO-3122) which increases endogenous PGH2, and sodium (E)-2-methyl-3-[4-3-pyridylmethyl)phenyl]-2-methylpropenoate (OKY-1581) which inhibits thromboxane A2 synthesis, on vasopressin-induced osmotic water flow in the bladder of the toad, Bufo bufo japonicus, were examined. ONO-3122 significantly inhibited the vasopressin-induced water flow at a concentration of 1 × 10–4M. OKY-1581 inhibited the vasopressin-induced water flow at 1 × 10–6 M, but enhanced it at 1 × 10–4M. These results suggest that ONO-3122 indirectly inhibits the vasopressin-induced osmotic water flow in the toad bladder; that is, ONO-3122 causes an increase in the conversion of arachidonic acid into PGH2. These results also suggest that OKY-1581 at a low concentration suppresses the vasopressin-induced water flow due to inhibition of cyclooxygenase activity. Both ONO-3122 and OKY-1581 provide a useful means for studying the action of prosta

ISSN:0031-7012    

DOI:10.1159/000138095

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Pretreatment of rabbits with phenobarbital caused significant increases in total pulmonary cytochrome P-450 content, benzo(a)pyrene hydroxylase and 7-ethoxycoumarin O-deethylase activities and to a lesser extent in benzphetamine N-demethylase activity in lung microsomes. However, 7-ethoxyresorufin O-deethylase activity was not significantly altered. In addition, the pulmonary concentration of the cytochrome P-450-metyrapone complex was increased significantly. Column chromatography of the pulmonary monooxygenases demonstrated that in untreated and phenobarbital-treated rabbits, cytochromes P-450I and P-450II constituted the major forms of cytochrome P-450 isozymes. In addition, the chromatographic studies showed that pretreatment with phenobarbital caused an increase in the content of cytochrome P-450I, but not of cytochrome P-450II. These observations were confirmed by subjecting the pulmonary cytochromes to gel electrophoresis, and staining of the gels for protein and heme.

ISSN:0031-7012    

DOI:10.1159/000138096

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Plasma amsacrine kinetics have been studied in rabbits after different doses (2.5–10 mg/kg) infused over 35 min. Amsacrine concentrations were measured by HPLC and plasma protein binding by equilibrium dialysis. All elimination curves were best fitted by a bi-exponential expression with a mean t½α of 0.56 h and t½β 5 mg/kg, there appeared to be an overproportional increase in the area under the curve, suggesting nonlinear kinetics. Comparison of pharmacokinetic parameters indicated a significant decrease in plasma Cl after the 10-mg/kg dose compared to the 5- and 2.5-mg/kg dose. Amsacrine was highly bound by plasma (96.8%) over the concentration range 1–100 μmol/l. It is concluded that the rabbit is an acceptable model for further studies of the pharmacokinetics of amsacrine and its analogues at doses

ISSN:0031-7012    

DOI:10.1159/000138097

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Rats were starved for 24 h. Morphine sulphate (1.0, 2.0 or 4.0 mg/kg i.p.) or naloxone-HCl (12.5, 25 or 50 mg/kg i.p.) was administered prior to 3 h of cold-restraint stress. Morphine at 4.0 mg/kg significantly reduced the ulcer severity relative to saline-injected controls and to naloxone-treated rats. Naloxone increased the ulcer incidence and ulcer severity when compared to controls and morphine-treated rats. These results suggest that endogenous opioids released during stress may attenuate the pathological effects of stress.

ISSN:0031-7012    

DOI:10.1159/000138098

出版商:S. Karger AG    

年代:1985

数据来源: Karger