Healing of acetic acid-induced gastric ulcer and gastric mucosal PGI2 level in rats.

The present study was designed to investigate the changes in gastric mucosal PGI2 level accompanying the healing of acetic acid-induced gastric ulcers in rats. The ulcers, which were observed with an endoscope, were found to undergo periods of decrease, healing and exacerbation during the rat's lifetime. The phases were categorized as follows: (1) the reduction period (days 3-50 after ulcer induction, corresponding to 7-14 weeks of age), (2) healing period (days 35-150 after ulcer induction, corresponding to 12-29 weeks of age), (3) first exacerbation period (days 35-231 after ulcer induction, corresponding to 12-40 weeks of age), (4) inactive period (days 231-365 after ulcer induction, corresponding to 40-60 weeks of age), and (5) second exacerbation period (days 365-550 after ulcer induction, corresponding to 60-86 weeks of age). In normal rats, the level of gastric mucosal PGI2 gradually increased with aging between 7 and 20 weeks, then decreased up to 40 weeks. The PGI2 level in the 60-week-old rat did not differ from that in the 40-week-old rat. The PGI2 level was the lowest in the 86-week-old rat. In ulcer-bearing rats, the PGI2 level showed the same pattern of change as that in normal rats, but the level was higher. The above results indicated a marked decrease in PGI2 level between 20 and 40 weeks of age and between 60 and 86 weeks of age in normal and ulcer-bearing rats. These periods corresponded closely to the first and second exacerbation periods, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Healing process of acetic acid-induced gastric ulcer and gastric mucosal prostaglandin E generation level in rats.

The prostaglandin E (PGE) generation level (PGE level) in the gastric mucosa was investigated in relation to the healing and relapse of acetic acid-induced gastric ulcers in the rat. The PGE level around ulcers showed higher levels after ulcer induction and decreased during the ulcer diminishing period. Thereafter, the PGE levels showed an inclination to increase during the ulcer exacerbation period. In reulcerated rats, PGE levels were significantly higher. In conclusion, a high level of PGE may indicate an ulcer exacerbation state.

Relapse of acetic acid-induced gastric ulcer and gastric mucosal prostaglandin I2 level in rats.

The healing process of acetic acid-induced gastric ulcer in rats was observed with an endoscope for 365 d after ulcer induction. The ulcers were induced by acetic acid solutions of various concentrations (2.5 (I), 5.0 (II), 10 (III) and 20% (IV); 0.05 ml). On day 3, a positive correlation was observed between the ulcer index (UI) and the concentration of acetic acid solution. On day 365, cumulative healing rates in groups I, II, III and IV amounted to 100, 100, 58.3 and 51.7%, respectively. The cumulative relapse rates in groups I, II, III and IV were 0, 13.6, 66.7 and 58.6%, respectively. Significant correlations were observed between initial UI values and cumulative healing or cumulative relapse rate. On day 365, rats were divided into two groups, a healed group and non-healed group, and the gastric mucosal prostaglandin I2 (PGI2) level was measured by bioassay. The PGI2 level around ulcers in ulcer-induced rats was higher than in normal rats, and it was higher in non-healed rats than in healed rats. Moreover, the PGI2 level was higher in those groups which showed a higher cumulative relapse rates. The above results indicated that the initial ulcer size and the PGI2 level around the ulcer might correlate to ulcer healing or exacerbation.

Evidence that the Na+-Ca2+ exchange system is related to the antiarrhythmic action of disopyramide.

1. Disopyramide induced a concentration-dependent decrease in action potential amplitude and Vmax, and prolonged action potential durations (APD50 and APD90) in ventricular muscle. 2. Na+-loaded membrane vesicles isolated from canine ventricular muscle rapidly accumulated Ca2+. 3. Monensin (10(-5) M) abolished Na+-dependent Ca2+ uptake, and Na+ enhanced Ca2+ efflux. 4. Na+-Ca2+ exchange by membrane vesicles was more active in preparations pretreated with disopyramide (10(-5) M) than in control membranes. 5. The results suggest that disopyramide changes Na+ influx from Na+ channel mediated to Na+-Ca2+ exchange mediated. This is verified in part by increased Ca2+ efflux.

A possible mechanism on the potentiated vascular effect of coadministration of ifenprodil tartrate and calcium hopantenate: a study in the basilar and vertebral arteries.

In our earlier report [Shibuya et al. in press], we demonstrated the partial mechanism of the synergism between ifenprodil tartrate and calcium hopantenate on cardiovascular diseases. The mechanisms of the synergistic effects in the basilar and vertebral arteries were further studied in this paper using our described methods. Ifenprodil tartrate produced a sustained increase in the vertebral arterial blood flow of rats, while calcium hopantenate. Ifenprodil tartrate caused dose-related relaxation of K+-induced contractions in by ifenprodil tartrate was significantly enhanced by the coadministration of calcium hopantenate. Ifenprodil tartrate caused dose-related relaxation of K+-induced contractions in isolated canine basilar arteries, while calcium hopantenate had no effect. The dose-relaxation curve of ifenprodil tartrate was shifted to the left by pre-incubation in calcium hopantenate. In K+-depolarized basilar arteries, ifenprodil competitively antagonized the response to Ca2+, and this was enhanced by pre-incubation in calcium hopantenate. Ifenprodil tartrate inhibited K+-induced Ca2+ uptake in canine cerebral arteries and this was enhanced by pre-incubation in calcium hopantenate. These results suggest that the enhancement by calcium hopantenate of the ifenprodil tartrate effect on the vertebral blood flow is due to increased vascular relaxation through the inhibition of Ca2+ influx.

A possible mechanism on the potentiating vascular effect of coadministration of ifenprodil tartrate and calcium hopantenate: a study in the internal carotid artery.

Recently, it has been proposed that the combined administration of ifenprodil tartrate and calcium hopantenate might produce a beneficial synergistic effect in the treatment of cerebrovascular diseases. To further examine this clinical phenomena, the blood flow in the internal carotid arteries of the rat and the isometric tension of canine internal carotid arteries were measured with a transit-time ultrasonic volume flowmeter and a force transducer, respectively. Ifenprodil tartrate produced a sustained increase in the internal carotid arterial blood flow of rats, while calcium hopantenate had no effect. However, the increase in the internal carotid arterial blood flow induced by ifenprodil tartrate was significantly enhanced by calcium hopantenate. Ifenprodil tartrate caused a dose-related relaxation of K+-induced contractions in the isolated canine internal carotid arteries, while calcium hopantenate had no effect. The dose-response curve of ifenprodil tartrate was shifted to the left by pre-incubation in calcium hopantenate. Ifenprodil tartrate inhibited the K+-induced Ca2+ uptake in the canine internal carotid arteries, and the inhibition induced by ifenprodil tartrate was significantly enhanced by calcium hopantenate. These results suggest that the observed enhancement by calcium hopantenate of the ifenprodil tartrate effect on the internal carotid arterial blood flow was due to increased vascular myorelaxation resulting from the influence of calcium hopantenate on the Ca2+ movement.

[A quantitative measurement of the cerebral infarct focus induced by arachidonate infusion and the relationship between measured values and stroke signs].

A method for measuring the organic infarct focus induced by arachidonate infusion into rat brain was devised, and the statistical relationship between the measured values and stroke signs in the rat was studied. By the infusion of arachidonate, a high incidence of cerebral infarction was found in the live rats with uniformly necrotized foci. The size of these foci (infarction rate) were measured by transcripting them to a graduated brain sheet. The relationship between the independent parameter of the infarction rate and the dependent parameter of stroke signs was fully analyzed by multidimensional quantification. Many animals showed no stroke signs despite having lesions (false negative). By contract, no animal without any lesion showed stroke signs (false positive). When each parameter of these signs were quantified and normalized, the stumbling and abnormal posture signs showed a wide range of values, relatively accurately reflecting the infarction degree. Moreover, the highest partial correlation ratio between the various parameters was found to be that between the stumbling and abnormal posture stroke signs. Thus, it may be said that the stumbling and the abnormal posture stroke signs can be considered relatively good parameters for evaluating the degree of an infarction. These parameters should be useful for the testing of anti-infarction drugs.

Effects of ifenprodil tartrate on alpha-adrenoceptors and Ca2+ movement in isolated canine saphenous veins.

The effect of ifenprodil tartrate (IFT) on 2 subtypes of postsynaptic alpha 1- and alpha 2-adrenoceptors was investigated. For this purpose, changes in the tension of isolated canine saphenous veins were measured isometrically, and Ca2+ uptake in these veins was also measured. IFT displaced the dose-contractile response curves for phenylephrine and clonidine in a competitive manner, and the activity sequence of antagonists against phenylephrine was IFT greater than phentolamine greater than prazosin greater than yohimbine. On the other hand, the activity sequence of antagonists against clonidine was IFT greater than phentolamine greater than yohimbine greater than prazosin. The effect of IFT as well as that of phentolamine were different from the other antagonists and of approximately the same specific activities against both agonists. The IFT-induced relaxations of the veins contracted by phenylephrine and clonidine were relatively unchanged in both normal and Ca2+-free solutions. IFT inhibited phenylephrine- and clonidine-induced Ca2+ uptake in the saphenous veins. The results suggest that IFT does not possess a relative selectivity toward postsynaptic alpha 1- and alpha 2-adrenoceptors, and that these actions reflect the vasorelaxing effects on phenylephrine- and clonidine-induced contraction in the canine saphenous veins.

[The mode for the manifestation of the inhibitory effects of ifenprodil tartrate on platelet aggregation in vivo and ex vivo].

The mode for the manifestation of the inhibitory effect of ifenprodil tartrate on platelet aggregation in vivo and ex vivo was studied in mice and men, respectively. The ifenprodil level in plasma reached the maximum in 20 min after oral administration of 30 mg ifenprodil tartrate/kg in mice, and it decreased over a 3 hr period after the administration. On the other hand, the maximal inhibitory effect was observed 60 min after the administration. Thus ifenprodil tartrate manifested its inhibitory effect on platelet aggregation only after the maximum plasma concentration of ifenprodil was reached. The same phenomenon was observed with the inhibitory effects of ifenprodil tartrate on platelet aggregation ex vivo in man. To clarify the reason for the delay in the manifestation of the inhibitory effects of ifenprodil, the ifenprodil contents in mouse platelets after the oral administration of the drug was measured. The pattern of change in the ifenprodil contents in platelets was found to resemble closely the pattern of the change in its inhibitory effects, suggesting that the manifestation of the inhibitory effects on platelet aggregation by oral administration of ifenprodil tartrate was directly related to the ifenprodil contents in platelets rather than the ifenprodil level in plasma.

Effects of ifenprodil tartrate on vertebral, basilar and internal carotid arteries.

Changes in blood flow of vertebral and internal carotid arteries of rats after the administration of ifenprodil tartrate were measured using the transit-time ultrasonic volume flowmeter. Tension of isolated canine basilar and internal carotid arteries was also tested isometrically. Ifenprodil tartrate produced a sustained increase in both vertebral and internal carotid arterial blood flow of rat. The increase in blood flow was greater in vertebral than in internal carotid arteries. Papaverine hydrochloride transiently increased arterial blood flow in both the vertebral and internal carotid arteries to approximately the same extent. Ifenprodil tartrate induced dose-related relaxation in basilar and in internal carotid arteries contracted with K+ (50 mM), and its effects were greater in basilar than in internal carotid arteries, while relaxation induced by papaverine hydrochloride was about the same in both arteries. These results suggest that the significant increase of vertebral arterial blood flow induced by ifenprodil tartrate is due to the peculiarity of vascular myorelaxation by this drug.

Effects of ifenprodil glucuronide derivative on platelet aggregation and vasocontraction.

It has been supposed that ifenprodil glucuronide derivative, detectable in large amount in rabbit plasma, is related to the pharmacological actions by ifenprodil tartrate. However, a synthesized ifenprodil glucuronide derivative was found to have no effect on platelet aggregation and vasocontraction in vitro. These results indicate that ifenprodil itself rather than its glucuronide derivative manifested the pharmacological actions.

[Effects of ifenprodil tartrate on erythrocyte deformability and cerebral blood flow].

Effects of ifenprodil tartrate on whole blood filtrability ex vivo in rats was investigated by a standard technique for measuring whole blood filtration time passed through a filter (5 micron). Ifenprodil tartrate was observed to reduce the filtration time dose-responsively. This effect was especially evident at 20 mg/kg (P less than 0.05). On the other hand, no effect on the hematocrit value, plasma concentration of fibrinogen, erythrocyte count or mean cellular volume of erythrocytes was observed. These results indicated the increasing effects ex vivo of ifenprodil tartrate on erythrocyte deformability. The ex vivo effects on erythrocyte deformability was manifested without changing the ATP contents, ATP/ADP ratio or adenylate energy charge in erythrocytes; and a phenothiazine-like amelioration in the shape of crenated erythrocytes was observed. These results suggested that the effect of ifenprodil tartrate on erythrocyte deformability ex vivo might be due to direct action on the erythrocyte membrane. At 0.3 mg/kg, i.v., ifenprodil tartrate significantly (P less than 0.05) increased the blood flow in the hypothalamus of conscious rats. Thus, it was indicated that ifenprodil tartrate, which increases the erythrocyte deformability and the cerebral blood flow, is useful for the therapeutic treatment of cerebrovascular accidents.

Inhibitory effect of sodium salicylate on ADP-induced platelet aggregation and on 45Ca2+ uptake into platelets.

The effects of sodium salicylate (SS) on ADP-induced platelet aggregation and on a metabolism of calcium in platelets were studied, using gel-filtrated platelets (GFP). SS inhibited dose-responsively ADP-induced aggregation in the presence of fibrinogen and Ca2+. It was found that extracellular 45Ca2+ was rapidly taken up into platelets after stimulation by ADP, while SS significantly inhibited this activity. On the other hand, SS had no effect on platelet aggregation induced by 0.11-1.0 microM ionophore A23187. Therefore, it was found that the inhibitory effect of SS on ADP-induced platelet aggregation may be due to the inhibition of the active influx of extracellular Ca2+ into platelets during aggregation.

[Anti-platelet actions of salicylates: in vivo, ex vivo and in vitro effects of choline salicylate].

Effects of choline salicylate, sodium salicylate, choline chloride and acetylsalicylic acid on platelet aggregation in vivo, ex vivo and in vitro in mice were studied. These drugs all inhibited adenosine diphosphate (ADP)-induced respiratory depression, which is closely related to platelet aggregation in vivo, with choline salicylate showing the strongest inhibitory effect. Choline salicylate had a tendency to reduce the mortality of animals injected intravenously with endotoxin, but the other drugs had no such effect. The inhibitory effects of these drugs on ADP-induced platelet aggregation ex vivo were in the order of choline salicylate greater than acetylsalicylic acid congruent to sodium salicylate greater than choline chloride congruent to no effect, and plasma concentrations of protein-unbound salicylic acid at 1 hr after oral administration of drugs were in the order of choline salicylate greater than acetylsalicylic acid congruent to sodium salicylate. The in vitro effects of these drugs were in the order of choline salicylate congruent to sodium salicylate greater than choline chloride congruent to acetylsalicylic acid congruent to no effect. Therefore, it was considered that salicylic acid played an important role on the in vivo, ex vivo and in vitro effects of choline salicylate and that choline increased plasma concentrations of salicylic acid and consequently enhanced the in vivo and ex vivo effects of salicylic acid. Furthermore, the ex vivo effects of choline salicylate were found when ADP-induced platelet aggregation was measured with platelet-rich plasma prepared from blood collected with heparin as anti-coagulant, but not when blood was collected with citrate.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological actions of iprazochrome on the vascular system].

The pharmacological actions of iprazochrome (IC) on the vascular system were studied, and the following results were obtained: No death nor abnormal behaviors were observed in acute toxicity tests conducted on male and female mice and rats despite the administration of large doses of IC (10,000 mg/kg, p.o. and 80 mg/kg, i.v., respectively). IC inhibited dose-dependently platelet aggregation in vitro induced by arachidonate and ADP, whereas no effect was observed on ADP-induced respiratory depression in mice, which is closely related to platelet aggregation in vivo. The antiserotonergic actions of IC on the isolated external carotid arteries and femoral arteries in dogs observed in a noncompetitive manner were found to be 1/24 to 1/65 that of methysergide. On the other hand, IC showed no inhibitory effect on the paw edema of rats in vivo induced by serotonin. The inhibitory effect of IC on peritoneal dye leakage in mice was less than half that of phenylbutazone. IC prevented apoplexy in stroke-prone SHR (SHRSP) without lowering the blood pressure. Histological changes in the cerebrum of SHRSP were ischemic changes such as swelling of the neurons and shrinkage of the nuclei, mainly in the cerebral cortex and corpus striatum area.

[Inhibitory mechanism of ifenprodil tartrate on rabbit platelet aggregation].

The effects of dl-erythro-4-benzyl-alpha-(4-hydroxyphenyl)-beta-methyl-l-piperidine-eth anol tartrate (ifenprodil tartrate) on rabbit platelet aggregation in vitro and ex vivo were studied. Ifenprodil tartrate inhibited platelet aggregation in vitro induced by ADP, collagen and epinephrine. It also inhibited 5-hydroxytryptamine (5-HT) uptake into platelets and 5-HT release from platelets. Since these inhibitory effects of ifenprodil tartrate on the functions of rabbit platelets were similar to the effects of imipramine, the effects of ifenprodil tartrate may be due to the stabilizing action of ifenprodil tartrate on the platelet membrane. The platelet aggregation by ADP was significantly inhibited in rabbits after oral administration of ifenprodil tartrate, the maximal plasma level of ifenprodil being reached at 20 ng/ml ex vivo, while the maximal level was only 1/40 of the minimal concentration of ifenprodil tartrate necessary to inhibit platelet aggregation in vitro. These results indicate that factors other than ifenprodil tartrate acting directly on the platelets (e.g., PGI2 which is an endogenous inhibitor of platelet aggregation) are involved in inducing the inhibitory effects of ifenprodil tartrate on platelet aggregation ex vivo. The effects of ifenprodil tartrate on both PGI2 release from the aorta and the inhibitory effects of PGI2 on platelet aggregation in vitro were investigated: PGI2 was found to intensify the inhibitory effects of ifenprodil tartrate on platelet aggregation in vitro, but there was little effect, if any, on PGI2 release. Therefore, it is considered that the ex vivo effects of ifenprodil tartrate might be due to its interaction with endogenous PGI2 in the blood.

[Studies on anti-inflammatory agents. (5). Specific characteristic of bone changes in adjuvant arthritic rats with passage of time].

Adjuvant arthritic rats develop marked changes in the distal limb joints. These changes were observed by soft X-ray photography at appropriate intervals. It was confirmed that the "cotton wool appearance" surrounding the bones, which was readily discernible from the radiographs, was a good indicator for following the progression of bone damages. Standard radiographs were selected to represent the various bone changes based on the "cotton wool appearance". When the incidence rates of bone deformation confirmed on the basis of the above method were plotted against Weibull Probability Paper, the plots conformed with the Weibull distribution function. Thus, it was possible to evaluate bone changes in adjuvant arthritic rats by observing the "cotton wool appearance" surrounding the bones.

A method for monitoring ADP-induced thromboembolism in mice.

A method for monitoring ADP-induced thromboembolism in mice by means of the measurement of respiratory rate and depth was studied. The measurement were accurately carried out with a new method devised by us. In mice intravenously injected with 5-40 mg ADP/kg, it was found that the respiratory rate decreased transiently and dose-responsively, and that the platelet count also decreased transiently. On the other hand, no decrease in respiratory rate after administration of ADP was observed in neuraminidase-pretreated mice, in which the platelet count was significantly reduced. In the histological examination, platelet thrombi formed in the pulmonary vessels were observed 10 sec after administration of 10 and 40 mg/kg of ADP in mice which had not been treated with neuraminidase. The extent of thromboembolism at the dose of 40 mg/kg showed a tendency to be more marked than that at 10 mg/kg. Pretreatment with 300 mg dipyridamole/kg p.o. prevented the respiratory depression at 40 mg ADP/kg. However, with 10 mg dimorpholamine/kg i.v. or 30 mg warfarin/kg p.o., no preventive effect was observed. Therefore, it was concluded that it is possible to monitor ADP-induced thromboembolism in mice by means of the accurate measurement of the respiratory rate and depth.