PACAP stimulates the release of interleukin-6 in cultured rat Müller cells.

We have investigated the in vivo effect of PACAP on rat Müller cells that are the predominant glial element in the retina. Müller cells were treated with PACAP38, either alone or in the presence of the PACAP-selective antagonist, PACAP6-38. Cellular proliferation was determined by measuring the incorporation of bromodeoxyuridine, while interleukin-6 (IL-6) levels in the culture medium were examined using a B9 cell bioassay. In cultured rat Müller cells, the expression of PACAP receptor (PAC1-R) was assessed with immunohistochemistry using a PAC1-R-specific antiserum. PACAP stimulated IL-6 production in Müller cells at a concentration as low as 10(-12) M, which was not sufficient to induce cell proliferation. This elevation of IL-6 production was significantly inhibited by PACAP6-38. These data suggest that Müller cells are one of the target cells for PACAP, stimulating the release of IL-6, and providing a mechanism whereby PACAP exerts a significant neuroprotective effect in the retina.

[Efficacy and side effects of lidocaine by intravenous drip infusion in children with intractable seizures].

Intravenous drip infusions of lidocaine (IDIL; 1-5 mg/kg/h) were performed in ten patients with intractable seizures. The medication was very effective in five patients, whose seizures disappeared immediately after the treatment of IDIL. In four patients, the medication proved to be effective judging from decreased incidence of seizures. In one patient with intractable seizures, the therapy was not effective. In nine patients with the effective medication, five had generalized seizures and four had partial seizures. Side effects were observed in four patients. Two patients had muscle hypotonia, one had visual and auditory hallucination and another had bradycardia. These symptoms completely disappeared after the ceasing of IDIL. Serum concentrations of lidocaine at the appearance of the side effects ranged from 1.8 to 4.7 micrograms/ml, although the toxicity level is more than 5.0 micrograms/ml for arrhythmic adult patients. These findings suggest that the serum toxic level of lidocaine in children is different from that in adults, and that careful observation and appropriate management for the children with lidocaine therapy should be necessary, even though the serum level of lidocaine ranges within the therapeutic level.

[Cerebral cortical dysplasia associated with epilepsy: MRI and clinical aspects].

Clinical and electroencephalographic (EEG) studies were performed in nine patients with cerebral cortical dysplasia (CD). Interictal single photon emission computed tomography (SPECT) using 99mTc-hexamethyl propylene amine oxime were studied in four patients. A patient with hemimegalencephaly and agyria had poor outcome in both developmental and epileptic aspects. The prognoses of clinical seizures were generally related to the severity, location and size of CD. The size of the lesion was not always correlated with the clinical seizure outcome. Four patients had focal pachygyria. Clinical pictures were diverse in these patients. One patient underwent callosotomy for the control of intractable seizures. The others had no clinical seizures despite of the appearance of paradoxical discharges in the area of pachygyria. The distribution of CD detected by MRI did not always correlate with that of paradoxical discharges in EEG and/or hypoperfusional areas seen in SPECT. These findings suggest that a detailed neuroimaging study is useful to elucidate the epileptogenesis in patients with CD, and that all the cortical abnormalities in patients with intractable epilepsy are not detected by MRI.

[A successful treatment with a continuous intravenous lidocaine for a cluster of minor seizures in a patient with Doose syndrome].

We reported a 7-year-old girl with myoclonic-astatic epilepsy of early childhood (Doose syndrome). She had minor seizures (i. e. absence, atonic and myoclonic seizures) refractory to treatment with many kinds of anti-epileptic drugs as well as thyrotropin releasing hormone. Though she had suffered from long-lasting clusters of minor seizures, the treatment with continuous intravenous lidocaine successfully brought a case of prolonged remission of both clinical seizures and EEG abnormalities. It has been reported that lidocaine is effective mainly for partial seizures. The efficacy of lidocaine for generalize seizures, however, has been reported only in a few papers. We considered that the treatment with continuous intravenous lidocaine is indicated in patients with Doose syndrome presenting with a cluster of refractory minor seizures.

Tissue angiotensin-converting enzyme blockade by MC-838 (altiopril calcium) infused intravenously to miniature pigs: comparison with captopril.

The effect of a new orally active angiotensin-converting enzyme (ACE) inhibitor, calcium(-)-N-[(S)-3-[(N-cyclohexyl-carbonyl-D-alanyl)thio]-2-methyl- prolinate (MC-838, altiopril calcium), on cardiohemodynamics and tissue ACE activity was compared with that of captopril in the anesthetized miniature pig. MC-838 and captopril were infused i.v. for 1 or 3 hr at an equimolar rate of 20 and 10 micrograms/kg.hr-1, respectively. When MC-838 was infused i.v., captopril appeared in approximately 40% of MC-838 in serum, indicating that the amount of serum captopril during the equimolar concentration treatment with MC-838 corresponds to half of serum captopril after the dosing of captopril. During the infusion, the drugs did not significantly affect systemic blood pressure (SBP), heart rate (HR), renal blood flow (RBF) and renal vascular resistance (RVR). MC-838 and captopril, in a similar degree, attenuated the vasoconstrictor response to angiotensin-I (A-I) injected into the renal artery (i.a.), and enhanced the vasodilator one to i.a. bradykinin, 3 hr after the onset of the drug infusion. The animals were sacrificed at 1 and 3 hr after the onset of the infusion of MC-838 or captopril, and the ACE activity in serum and some target organs (lung, kidney, heart, brain and aorta) was determined. Effective activities of MC-838 and captopril occurred in the lung and kidney (only at 3 hr for captopril) where higher ACE activity in a variety of tissues was found, to a lesser degree in the serum (only by captopril) and not at all in the brain, heart and aorta.

A radioimmunoassay for MC-838 (altiopril calcium), a novel angiotensin-converting enzyme inhibitor.

A radioimmunoassay was developed for a new, potent inhibitor of angiotensin-converting enzyme (ACE; EC 3.4.15.1), calcium(-)-N-[(S)-3-[(N-cyclohexylcarbonyl-D-alanyl)thio]-2-methyl- propionyl]-L-prolinate (MC-838, altiopril calcium). The antiserum was obtained by immunizing rabbits with MC-838-bovine serum albumin (BSA) conjugate. MC-838-L-tyrosine labeled with 125I and purified by thin-layer chromatography was used as a tracer. The assay sensitivity was 0.1 ng/ml, the average intra-assay coefficient of variation was 7.9%, and the average inter-assay coefficient of variation was 13.7%. The antiserum was specific for MC-838, showing only slight crossreactivity with degradation products of MC-838. After a single oral dose of MC-838 (2 mg/kg), radioimmunoassay of MC-838 canine serum demonstrated rapid absorption from the gastrointestinal tract with a peak level of 40.6 ng/ml. The decline in serum concentration was a biphasic decay, with a half-life of 80 min during rapid falloff followed by a slower decline.

Effects of AN-132 and quinidine, antiarrhythmic agents, on plasma digoxin concentrations in rats.

The effects of AN-132, 3-(diisopropylaminoethyl-amino)-2',6'-dimethylpropionanilide.2H 3PO4, on chloroform-induced arrhythmias and plasma digoxin concentrations have been compared with those of quinidine in rats. AN-132 (0.01-3 mg kg-1) administered orally significantly inhibited the incidence of cardiac arrhythmias in a dose-related fashion. A single dose of digoxin (1 mg kg-1) given orally for 7 consecutive days was followed, on day 8, orally by digoxin alone, or together with AN-132 (50, 100 and 200 mg kg-1) or quinidine (25 and 50 mg kg-1). The AUC0-24 and Cmax of plasma digoxin were enhanced significantly by co-administration of quinidine, but not by AN-132.

MC-838 (altiopril calcium): a novel orally active angiotensin converting enzyme inhibitor.

MC-838, calcium (-)-N-[(S)-3-(N-cyclohexylcarbonyl-D-alanyl) thio]-2-methylpropionyl]-L- prolinate, is a new orally active angiotensin converting enzyme (ACE) inhibitor in which the mercapto-group is taken up in a stable thiolester linkage. The linkage was relatively resistant against enzymatic hydrolysis by rat liver homogenates. The ACE prepared from rabbit lung was inhibited by MC-838 in a concentration-dependent manner. In isolated rat aortic ring and guinea-pig ileum preparations, MC-838 was highly specific in suppressing the contractile response to angiotensin-I (A-I) an in augmenting the contractile one to bradykinin. However, the ACE inhibitory activity of MC-838 was 30-100 times less potent than that of captopril. In conscious two-kidney (2 KG), renal hypertensive rats and spontaneously hypertensive rats (SHRs), MC-838 (3 and 10 mg/kg) given orally caused a long-lasting hypotensive effect with a slow onset. When compared on a weight basis (3 mg/kg), the antihypertensive effect of MC-838 was comparable to that of captopril in magnitude, but the duration of action of MC-838 was approximately 2 times longer than that of captopril.

Effects of nicorandil and verapamil, antianginal agents, on plasma digoxin concentrations in rats and dogs.

The effects of equihypotensive doses of nicorandil and verapamil on plasma digoxin concentrations have been assessed in rats and dogs. In a single digoxin dose study, digoxin (1 mg kg-1) alone, or in combination with nicorandil (5 mg kg-1) or verapamil (25 mg kg-1) was given orally to rats. When given chronically to rats, a single dose of digoxin (1 mg kg-1) orally for 7 consecutive days was followed, on day 8, by digoxin alone, or together with nicorandil (5 mg kg-1) or verapamil (25 mg kg-1). In dogs, a loading dose of digoxin (50 micrograms kg-1) was given orally on day 1, then 25 micrograms kg-1 was administered for the following 6 days. On day 8, digoxin (50 micrograms kg-1) was given with nicorandil (5 mg kg-1) or verapamil (20 mg kg-1). In rats, the AUC0-24 and Cmax of plasma digoxin were enhanced significantly by coadministration of verapamil, but not by nicorandil. In dogs, verapamil significantly increased the Cmax of plasma digoxin, but not the AUC. Nicorandil had no effect on either parameter.

Hypotensive effects and biotransformation of nicorandil, a new antianginal agent, administered to rats by different routes: comparison with nitroglycerin and isosorbide dinitrate.

The effects of nicorandil, N-(2-hydroxyethyl)nicotinamide nitrate (ester), in reducing systemic blood pressure (SBP) in rats were studied in comparison with isosorbide dinitrate and nitroglycerin. The drugs were administered to pentobarbitone-anaesthetized rats by jugular vein (i.v.), portal vein (p.v.), intrajejunal (i.j.), intraperitoneal (i.p.) and subcutaneous (s.c.) routes. Nicorandil was absorbed rapidly through all routes, and caused marked hypotension dose-dependently. With isosorbide dinitrate and nitroglycerin, unlike nicorandil, the p.v. dose required to induce a vasodepressor response was significantly greater than that required to cause a comparable response after i.v. administration. In non-recirculating rat liver perfusion experiments, nicorandil was reduced only 5-10% during a single passage through the liver, while nitroglycerin was reduced over 95%. In recirculating liver perfusion experiments, the progressive decrease of nicorandil in the blood recirculated was accompanied by a corresponding increase of SG-86, a dinitrate compound of nicorandil (its main metabolite). Sixty min after dosing, nicorandil was decreased by approximately 73% of the initial nicorandil blood concentration and SG-86 was increased by approximately 70%. The extent of degradation of nicorandil in liver homogenates, examined by thin-layer chromatography, was in the following order: rat = guinea-pig greater than dog = monkey greater than pig. In these species a close inverse relationship is apparent between the rate of liver nicorandil degradation and hypotensive effects of nicorandil.

Feeding suppression induced by intra-ventricle III infusion of 1,5-anhydroglucitol.

1,5-Anhydroglucitol (1-DG) has been known as an antimetabolic glucose analogue. Using gas chromatography, 1-DG was found to be physiologically present in rat serum. In order to investigate its direct and long-term effects on feeding, 1-DG was infused during the light period into the rat third ventricle in doses of 3.0, 6.0 and 12.0 mumol/rat. Its effects were then compared to those of similarly applied 2-deoxy-D-glucose (2-DG). Following initial hyperphagia, both of these glucose-analogues produced suppressive effects on feeding during the subsequent day throughout the light and dark periods. On the third day after 2-DG injection reduction of feeding did not recover completely to the pretreatment baseline levels, but it did recover after 1-DG. Both 1-DG and 2-DG caused linear dose-related hypophagia, with the slope for 1-DG being about half of that for 2-DG. It is suggested that the delayed hypophagia which followed the initial hyperphagia produced by deoxyglucose was a result of sustained inactivation of the Na-pump due to intracellular ATP deficiency caused by accumulation of deoxy-glucose-6-phosphate.

Specific binding of sucralfate in gastric ulcer and gastritis.

The binding moiety of sucralfate to gastric mucosal sites, such as gastric ulcers and areas of gastritis, was studied in humans. The methods used to elucidate this binding were chemical assay of sucralfate, gastroscopic examination, and histological diagnosis in 39 patients with gastric ulcer and ten patients with gastritis. Sucralfate was observed in the gastric ulcer, and sucrose sulfate ester and aluminum were detected selectively in the lesions. In cases of chronic gastritis, there was no correlation between histological changes and the binding of the sucralfate, but the amount of adhesive mucus and the state of congestion were significantly correlated with the binding of sucralfate.

Effect of sucralfate on ethanol-induced gastric mucosal damage in the rat.

We studied the effect of sucralfate on ethanol-induced gastric mucosal damage in the rat. In doses of 25, 50, 100, 200, 400 and 800 mg/kg given 1.5 hr before the oral administration of 3 g/kg ethanol, sucralfate inhibited the development of erosions by 36, 62, 72, 90, 98 and 100 percent, respectively. Cimetidine, up to a dose of 160 mg/kg, was ineffective in this model. Sucralfate, in a dose of 400 mg/kg, also decreased the drop in transmucosal potential difference produced by the intragastric instillation of 3 ml of 20% ethanol from 21 mV to 13 mV. In separate experiments, pylorus-ligated rats received 125I-labeled human serum albumin intravenously and the leakage of 125I-radioactivity into the gastric lumen was studied as a parameter of mucosal permeability to macromolecules. Ethanol, in a dose of 3 g/kg, produced a two-fold increase in leakage over control. This was prevented by sucralfate (250 mg/kg) when given either 1.5 hr before or 3 hr after the dose of ethanol. The results of these experiments suggest that sucralfate protects the gastric mucosa against ethanol-induced damage by enhancing mucosal resistance.

Binding of sucralfate to duodenal ulcer in man.

Biopsy specimens of ulcerated and of adjacent non-ulcerated duodenal mucosa were obtained from 17 patients with active duodenal ulcer who had received a single oral dose of 1 g sucralfate. Similar specimens were obtained from 21 patients with a recently healed duodenal ulcer. The specimens were assayed for aluminum to provide an estimate of the amount of sucralfate bound to the mucosa. Sucralfate was present at significantly higher concentrations in ulcerated mucosa than in non-ulcerated mucosa for 6 hr after dosing. In addition, sucralfate was found to bind to healed duodenal ulcers for 6 hr after dosing. This finding provides a rational basis for the use of sucralfate in the maintenance therapy of duodenal ulcer.

Pharmacodynamic and metabolism studies on a new coronary vasodilator, N-(2-hydroxyethyl) nicotinamide nitrate (SG-75).

Pharmacodynamics and metabolism of N-(2-hydroxyethyl) nicotinamide nitrate (SG-75) were investigated in rats in relation to its main metabolic product. When SG-75 was orally administered, SG-75 and SG-86, a denitrate compound of SG-75, appeared in the blood. Within 7 yr, approximately 60% of the administered SG-75 were recovered in the urine as SG-86. When administered intraduodenally, SG-75 was rapidly absorbed and transferred in an unaltered form into the portal vein. SG-75 possessed hypotensive and coronary vasodilating actions, while SG-86 had little effect on the cardiovascular system. The coronary vasodilating effects of SG-75 k(0.3-20 micrograms i.a.) were unaffected by the continuous infusion of SG-86 into the coronary perfusion system, even in large doses (50 micrograms/min, or 500 micrograms/min).

Vascularly perfused rat small intestine: a research model for drug absorption.

Rat isolated small intestine was perfused at a fixed flow rate through the superior mesenteric artery with whole rat blood recycled from a devised oxygenator-reservoir. As indicated by perfusion pressure, tissue glucose and oxygen consumption, and histological studies, the perfused intestine remained in a viable state over the perfusion period of 2 hr. Rapid absorption of glucose from the intestinal tract was observed after the intraduodenal injection. When single doses of acetaminophen were injected into the duodenal lumen or poured over the perfused intestine, the absorption was rapid and dose-dependent. Shortly after single intraduodenal injections of salicylamide, salicylamide in free and conjugated forms (sulfate and glucuronide) appeared in the circulating blood. These results indicate that the vascularly perfused intestinal preparation has wide applications in biochemical experimental fields.

Selective binding of sucralfate to ulcer lesion. II. Experiments in rats with gastric ulcer receiving 14C-sucralfate or potassium 14C-sucrose sulfate.

14C-Sucralfate, a basic aluminum salt of 14C-sucrose sulfate, or potassium 14C-sucrose sulfate was administered orally to rats with acetic acid-induced gastric ulcer. The radioactivities representing specific binding of the sucrose sulfate moiety were found significantly higher in ulcer sections of the stomach, with the mean within-animal ulcer/non-ulcer ratio attaining 6, 7, 12 and 2.5, respectively, at 1, 3, 6 and 24 h after 14C-sucralfate administration. Microautoradiography provided direct in vivo evidence for binding of the 14C-sucrose sulfate moiety to exuded proteins resulting in effect in formation of a pepsin-resistant barrier over the surface of an ulcer crater. No comparable findings were obtained in the area of normal mucosa. The administration of 14C-sucralfate was associated with much greater and longer-sustained binding to the ulcer lesion and retention in the stomach and duodenum than simple administration of the soluble potassium salt. These findings not only demonstrate therapeutically significant effects of basic aluminum compoundation but also substantiate likely differences from pepsin inhibitors such as amylopectin sulfate in terms of presence or absence of adhesiveness, local barrier effects, and long duration of actions.

Selective binding of sucralfate to ulcer lesion. III. Experiments in rats with duodenal ulcer receiving 14C-sucralfate.

To determine whether the previously reported mechanisms of action of sucralfate for gastric ulcer are also operative in duodenal ulcer, a single dose of 14C-labelled sucralfate was administered orally to rats with acetic acid-induced duodenal ulcer. Adhesive coating with sucralfate was visible over the duodenal lesion for 6 h in the majority of animals and found localized increasingly selective to the ulcerous area following administration. Visual observations were supported quantitatively by greater than unity mean within-animal ulcer/non-ulcer ratios of binding by 14C-sucrose fulfate moiety and aluminum, with statistical significance at 3 and 6 h post-administration (P less than 0.01 or 0.05). While the aluminum component was found persistent relative to the sucrose sulfate moiety in the adhesive coating, an additional in vitro study revealed that this was due to the pH of duodenal contents and did not lead to a loss of adhesiveness. In addition to these results, the buffering potential of sucralfate coating to control the local pH condition sufficient for binding to ulcer surface proteins to occur support the conclusion that the same mechanisms of action of sucralfate commonly apply to gastric and duodenal ulcers.