The anticholinergic drug propiverine inhibits the protein kinase C activity in the rat urinary bladder.

UNLABELLED: There is ample evidence that non-cholinergic protein kinase C (PKC) mediated signal transduction pathways are involved into regulation of bladder smooth muscle contractions. To evaluate whether the anticholinergic and calcium modulating drug propiverine exerts intracellular effects by inhibition of the PKC, male inbred LEW 1A rats were pretreated with 0.6, 2, 6 and 60 mg/kg body weight for 5 days. Furthermore, competition assays with partially purified PKC were performed with propiverine in vitro. The activities of the membrane-bound and soluble PKC were assessed by 32P enrichment of lysine-rich histone. RESULTS: The active, membrane-bound PKC decreased by about 60% accompanied by increase of the soluble form after propiverine in doses above 0.6 mg/kg. 100 nM of the drug inhibited the PKC also in vitro whereas the propiverine metabolites M5 and M6 and atropine were without any effect. CONCLUSIONS: Propiverine was identified to be an inhibitor of the protein kinase C. Its contribution to the noncholinergic control of hyperactive detrusor smooth muscle cells needs further investigation.

Formaldehyde inhalation & open field behaviour in rats.

BACKGROUND & OBJECTIVES: It has been shown in animal studies that repeated exposure to formaldehyde vapour alters behaviour and memory. Since information is not available on the behavioural consequences of acute formaldehyde exposure, this study was conducted to investigate the influence of single inhalative exposure to formaldehyde on the explorative and locomotor behaviour of adult male and female rats. METHODS: Rats were exposed to different concentrations of formaldehyde vapour (0.5, 1.0, 2.5%, corresponding to inhalation chamber concentrations of 1.0, 2.5, and 5.0 ppm, respectively) for 2 h and an open field test was carried out 2 h after the end of exposure (first test) and repeated 24 h thereafter (second test). The parameters examined were crossing of floor squares, sniffing, grooming, rearing, climbing, and defaecation. RESULTS: In exposed male rats, significant reduction of crossed floor squares, grooming, and wall climbing, and increase in floor sniffing and rearing were observed in the first test. During the second test, males in the groups exposed to 2.5 ppm and 5 ppm crossed significantly higher numbers of squares when compared to controls. Air sniffing, wall climbing, and rearing were altered in all exposed males. Control males showed higher incidence of defaecation in comparison to the values of first test. The formaldehyde-exposed female rats crossed significantly decreased numbers of floor squares in the first test. In females in the 2.5 ppm and 5 ppm groups, decreased grooming and enhanced floor sniffing were observed. In the second test, all exposed females crossed higher numbers of floor squares than controls. Frequencies of air and floor sniffing were higher in females exposed to 2.5 ppm and lower in those exposed to 1 ppm. Defaecation was enhanced in females in the 2.5 ppm group in comparison to the first test. INTERPRETATION & CONCLUSION: The results show that formaldehyde inhalation in the concentrations and duration of exposure used in the present experiments significantly influences the locomotor and explorative behaviour of rats after a single exposure in a gender-related manner and that various behavioural components in the exposed animals remains altered even after 24 h.

Sex-related differences in procarbazine-induced cleft palate and microgenia and the anti-teratogenic effect of prenatal folic acid supplementation in rats.

Sex-related differences in the frequency of cleft palates and microgenia in rat fetuses prenatally treated with procarbazine (200 mg/kg on day 14 of gestation (GD14), group 1), and the anti-teratogenic effect of prenatal folic acid supplementation (4 mg/kg on GD14 through GD17, group 2) were studied in LEW.1A rats. In group 1, complete clefts were observed in 69% of the male and in 36% of the female fetuses while incomplete clefts (present only in the hard palate) were exhibited by 31% of the males and 43% of the females. Microgenia occurred in all males but only in 64% of the female fetuses. In group 2, the prenatal folic acid supplementation significantly reduced the occurrence frequency of complete clefts to 9% in males and to 0% in females. In contrast, incomplete clefts increased to 82% in males and 91% in females. Microgenias were reduced to 73% and 57% in male and female fetuses, respectively. Since incomplete clefts present in the hard palate are assumed to be residues of spontaneous intra-uterine repair processes of exogenously induced complete palatal clefts, we conclude that prenatal supplementation with folic acid at a dose of 4 mg/kg promotes the intra-uterine repair of cleft palates and offers a partial protection against procarbazine teratogenicity. Furthermore, it is deduced that gender-specific differences exist in the susceptibility to procarbazine and in the anti-teratogenic effect of folic acid on procarbazine-induced microgenia.

A study on the effect of inhalative formaldehyde exposure on water labyrinth test performance in rats.

We investigated the effects of repeated inhalative exposure to several formaldehyde concentrations (2 hours/day, 10 consecutive days) on the behavior of adult male and female LEW.1K rats during a period in which they learned to perform a water labyrinth task. We also examined the effects on the histology of some organ tissues. While the controls needed increasingly shorter swimming periods to complete the water labyrinth test and made fewer errors with advancing trial duration, such progress could not be observed in the learning behavior of the exposed animals. They took significantly longer swimming periods to reach the finish and made significantly more errors in comparison to the controls. The statistical comparison between the collected data in the formaldehyde exposed male and female rats reveals that females in general reached the end point of the swimming labyrinth in significantly less time. On some trial days, however, they made more mistakes than males. In the highest concentration group, no gender differences were evident in the frequency of errors. The histological examination revealed no pathological changes attributable to formaldehyde exposure. Since the water labyrinth test is used to investigate changes in memory and learning behavior in animals, we conclude that under investigational conditions, formaldehyde affects the learning behavior and the memory of male and female rats.

Effects of prenatal procarbazine administration on intrauterine development in rats.

The effects of prenatal procarbazine (PCZ) administration on the intrauterine development of rat fetuses were investigated. Gravid rats were treated on day 14 of gestation (GD14) with 25 mg or 50 mg/kg body weight PCZ via stomach tube. Controls received normal saline in the same dosis and manner. On GD20, all fetuses were collected by caesarian section. Live and dead fetuses as well as resorptions were counted. In the live fetuses, the following investigations were conducted: measurement of body weight, occipito-coccygeal-lenght (OCL), tail length (TL), placental weight and diameter, external macroscopic and binocular microscopic examination, and sectional analysis of the animals using the razorblade sectioning technique. Both PCZ doses caused a significant reduction in the number of live fetuses and a significant increase in resorptions. Mean body weight in PCZ groups was antidromic affected. OCL and TL were significantly depressed. Placental weight and diameter as well as number of dead fetuses were comparable to those of controls. External and sectional investigations revealed no PCZ-related deviations. In the light of our findings we conclude that PCZ in the doses used in this experimental study significantly affects the intrauterine development in rats in terms of fetal toxicity but displays no teratological properties.

Is it possible to prevent cleft palate by prenatal administration of folic acid? An experimental study.

OBJECTIVE: In this study, folic acid was tested for its antiteratogenic effects on experimentally induced cleft palate in animals. DESIGN: Eleven pregnant Lew 1 A dams (75 fetuses) received 200 mg/kg procarbazine via gastric tubing on postconception (p.c.) day 14 to induce a cleft palate (CP); seven of the pregnant dams (45 fetuses) were additionally given 4 mg/kg folic acid subcutaneously from the 14th to the 17th day p.c. As a control group, three more pregnant dams (24 fetuses) were not treated with the drugs mentioned above. All fetuses were delivered by Caesarian section on day 20 p.c. OUTCOMES MEASURED: All fetuses were weighed and examined macroscopically with a stereomicroscope. Each fetal head was cut into 35 frontal sections and scrutinized histologically. RESULTS: None of the control fetuses (n = 24) exhibited a cleft. Without folate administration, 90% of the fetuses (27 of 30) that received procarbazine exhibited a CP. After additional prenatal folate administration, this rate remained virtually unchanged (91%; 41 of 45). However, the proportion of complete (total) CP (4%) was significantly (p <.0001) lower than in the group without folate (53%). Cleft-associated microgenia and microglossia were also significantly less frequent when folate was administered prenatally: microgenia was reduced by 22% (p =.029) and microglossia by 24% (p =.032). CONCLUSIONS: On the basis of these results, folate has a partial ameliorating effect on the teratogenicity of procarbazine given to pregnant rats. Additional studies are necessary on the effect of folate in different species, also taking cleft lip and CP into consideration.

Endocrine effects of dopexamine vs. dopamine in high-risk surgical patients.

OBJECTIVES: To compare the endocrine effects of dopexamine and dopamine on prolactin (PRL), dihydroepiandrosterone sulfate (DHEAS), cortisol, thyrotropin (TSH), and peripheral thyroid hormone serum concentrations in surgical patients at risk of developing postoperative complications because of hypoperfusion of various organ systems. DESIGN AND SETTING: A prospective, randomized, placebo-controlled, blinded clinical trial in an adult surgical intensive care unit in a university hospital. PATIENTS: Thirty-two male surgical risk patients undergoing elective major abdominal surgery. INTERVENTIONS: Patients were randomized to receive placebo ( n=8), dopexamine (0.5 microg kg(-1) min(-1), n=8), dopexamine (1 microg kg(-1) min(-1), n=8) or dopamine (5 microg kg(-1) min(-1), n=8) on the first postoperative day. MEASUREMENTS AND RESULTS: All patients received either a placebo or catecholamine infusion for 24 h. Blood samples were obtained every 2 h for the next 2 days. PRL, DHEAS, cortisol, TSH, triiodothyronine, thyroxin, free triiodothyronine, and free thyroxin serum concentrations were determined by radioimmunoassay or luminescence immunoassay. Dopexamine (0.5 microg kg(-1) min(-1)) had no effects on serum concentrations of PRL or TSH. Higher doses of dopexamine (1 microg kg(-1) min(-1)) suppressed PRL secretion significantly, but not TSH. In contrast, infusion of dopamine (5 microg kg(-1) min(-1)) completely inhibited PRL and TSH secretion. DHEAS, cortisol, and thyroid hormone serum concentrations were not affected by either dopexamine or dopamine infusion. Measurements of hemodynamic parameters, peripheral oxygen saturation, diuresis, blood gases, and standard laboratory parameters were repeated hourly. Significant differences were not found between placebo, dopexamine (0.5 microg kg(-1) min(-1)) and dopamine (5 microg kg(-1) min(-1)) group. Dopexamine at 1 microg kg(-1) min(-1) increased the heart rate significantly. CONCLUSIONS: Routine postoperative optimizing of men undergoing abdominal surgical procedures with dopexamine at higher doses or dopamine induces at least partial hypopituitarism, which may possibly affect postoperative morbidity.

Cheilognathopalatoschisis and its prophylaxis in animal experiments.

Cheilognathopalatoschisis (cleft lip, -maxilla, and -palate) is the second most frequent malformation in humans. The ontogenetic causes are mostly multifactorial. Some researchers have succeeded in lowering the frequency of occurrence of such clefts in children of predisposed women by giving the latter an applied symptomatic replacement therapy with multivitamin preparations or other substance classes during early pregnancy. However, the dosage of these substances was only anecdotal and their effect unspecific. Many research groups world-wide are conducting animal experiments in order to investigate the efficacy of vitamins and other substances as prophylactics. The experiments are usually conducted with laboratory rats and mice, and clefts are often induced by applying chemical noxa. The results of these trials, however, are controversial. Where some authors were able to prove protective effects of the vitamins or other substances they employed, others found evidence that such replacement therapy has no prophylactic effect. This paper provides insight into such studies with experimental animals, and compares their results.

Interferon- and streptolysin O-induced activation of protein kinases and inhibition of cytochrome P450-dependent monooxygenases in rats.

Immunostimulants known to initiate cytokine production were found to decrease the activity of hepatic microsomal drug oxidative enzymes but to activate protein kinase C (PKC). The present study investigated the effects of immunostimulating doses of rat interferon-gamma (IFN, 670,000 units i.p.) and streptolysin O (SLO, 100 HU/kg i.v. for 5 days) on hepatic soluble, membrane-bound and nuclear PKC, 7-ethylresorufin-O-deethylase (EROD) and 7-pentylresorufin-O-deethylase (PROD) in male Wistar rats. The SLO- and IFN-mediated decrease of EROD and PROD activity was associated with a characteristic activation of the hepatic and spleenic PKC. In SLO- and IFN-treated animals activities of the cytosolic, membrane-bound and nuclear PKC were significantly higher than in respective controls. Our results suggest that a decrease in hepatic cytochrome P450 content as well as the decrease in the EROD and PROD activities are inversely related to the function of PKC.

A single and multiple dose bioavailability study with carbamazepine 400 mg retard tablets with reference to enzyme autoinduction and circadian time differences.

UNLABELLED: Both single and multiple dose bioequivalence studies are required to assess the quality of modified release formulations of drugs. In bioequivalence studies of drugs with enzyme autoinducing properties such as carbamazepine (CBZ), the standard multiple dose study design must be modified to guarantee equivalence of drug elimination. This problem was considered with regard to carbamazepine 400 retard AWD (test) whose bioavailability relative to a listed reference (Tegretal 400 retard) was studied in 2 randomized, open, crossover studies both with 18 healthy volunteers of Caucasian origin (20-36 years, 61.5-92 kg, 172-195 cm). The single dose study was done with 400 mg CBZ. Serum concentration time profiles of CBZ and its active metabolite CBZ-10,11-epoxide were determined until 144 h after administration. The multiple dose study was performed with 400 mg CBZ b.i.d. for 15 days (first 2 days: 200 mg b.i.d.) followed by a 7-day study with the alternative investigational product. 24-hour serum concentration time profiles of CBZ and its metabolite were measured on days 15 and 22 of the study. The quantitative drug analysis was done with an HPLC method the quality of which fulfilled the requirements of bioequivalence studies. Test was considered bioequivalent to reference with regard to the extent of absorption, if the 90% confidence intervals of the AUC0-infinity ratio (single dose) and AUC0-24h ratio (multiple dose) were within the range of 0.80-1.25, and with regard to rate of absorption if the 90% confidence intervals of the Cmax/AUC ratio (single dose) or AUCF0-24h ratio were within 0.70-1.43. The point estimators (90% confidence limits) of the AUC ratio (test/reference) of CBZ were 0.979 (0.94, 1.02) for the single and 1.01 (0.947, 1.076) for the multiple dose comparison. The point estimator (90% confidence limits) of the Cmax/AUC ratio was 0.989 (0.959, 1.020) and of the AUCF0-24h ratio 1.066 (0.937, 1.212). There were no circadian time differences in any pharmacokinetic parameter. IN CONCLUSION: Carbamazepine 400 retard AWD tablets were bioequivalent to reference with regard to extent and rate of absorption after both single and multiple dose administration.

Circadian-time rhythm of hepatic protein kinase C of rats pretreated with phenobarbital.

Circadian-time dependent differences of protein kinase C (PKC) activities as well as its susceptibility to a phenobarbital caused suppression in vivo (40 mg/kg b.i.d. for 3 days) were studied in outbred male Wistar rats weighing 280-360 g. The well-known phenobarbital induction of cytochrome P-450 and 7-pentylresorufin-O-depentylase (PROD) was associated with inhibition of the hepatic PKC. The activities of the cytosolic and membrane-bound PKC were significantly lower than in the respective controls. Statistically significant circadian-time differences were found. The activities of both cytosolic and membrane-bound PKC of control rats were highest in the evening (158% and 131%, respectively, of the morning values). Furthermore, phenobarbital inhibited the enzyme more strongly at 19.00 h than at 07.00 h. Our results suggest that increase of hepatic cytochrome P-450 content as well as induction of PROD are inversely related with the function of PKC.

[The effect of 2,4-dichlorophenol on enzyme activities and other parameters in parenchymatous organs of rats]. / Zur Wirkung von 2,4-Dichlorphenol auf Enzymaktivitäten und andere Parameter in parenchymatösen Organen von Ratten.

After repeated administration of 2,4-dichlorophenol the aminopeptidases AAP and LAP, and the alkaline phosphatase in various organs were influenced. The treatment causes stimulatory or inhibitory activities. Also with histological and histochemical methods damages could be detected.

[The covalent binding of a potent beta-receptor blocker (B 24/76) on tissue proteins and collagen in the rat]. / Untersuchungen zur kovalenten Bindung eines potentiellen beta-Rezeptorenblockers (B 24/76) an Gewebsproteine und Kollagen bei der Ratte.

Toxic effects of drugs and their metabolism may be caused by covalent binding to cellular macromolecules. After oral application of the tritiated beta-blocker B 24/76 to male Wistar rats only the liver showed a significant irreversible binding to tissue proteins, with 11% of the radioactivity distributed in this organ. A covalent binding to collagen was found in liver, lung and muscle. The highest part was measured in the lung with 7% of the radioactivity distributed in this organ.

Membrane-associated signal transduction modulates contractile responses to Ca2+ in saponin-skinned coronary smooth muscle.

Experiments on saponin-permeabilized bovine and porcine coronary arteries were performed to examine whether fluoride-induced contractile mechanisms are retained after permeabilization and whether they modulate muscle tension without a change in cytoplasmic Ca2+. Fluoride induced reversible contractions in skinned coronary smooth muscle and shifted the apparent Ca2(+)-sensitivity of the contractile system to lower Ca2+ values. Force development to fluoride required exogenous ATP and a minimum Ca2+ concentration (pCa less than 8) of the bathing medium. Force development occurred when the concentration of free Ca2+ available to the contractile apparatus seemed to be sufficiently controlled by a Ca2(+)-EGTA buffering system. The effects of fluoride were enhanced by Al3+ and imitated by both guanylyl-imidodiphosphate and 4 beta-phorbol-12,13-dibutyrate which suggests the involvement of both GTP-binding protein(s) and of the C-kinase pathway. Under conditions of sufficiently controlled Ca2+ buffering, saponin-skinned arteries responded to histamine or carbachol with an increase in muscle tension which was inhibited by specific receptor blocking agents (diphenhydramine, atropine), and which required the presence of both exogenous ATP and a low concentration of Ca2+ (pCa 7) which per se did not result in a contractile response. It is concluded that agents acting on different steps of membrane-associated signal transduction pathways are able to induce contractile responses of saponin-skinned vascular smooth muscle without a change in cytosolic Ca2+ concentration.

[Serotonin uptake of thrombocytes as a measure of thrombogenicity of adsorbents]. / Serotoninaufnahme der Thrombozyten als Mass für die Thrombogenität von Adsorbentien.

Serotonin intake into platelets is an active carrier-mediated metabolic achievement. This uptake may be reduced by unphysiological irritation on platelet membrane. Therefore, it is suitable for judgement of thrombogenicity of biomaterials. The 14C serotonin intake after blood contact with various adsorbents was investigated: Haemoresin (GDR), Adsorba 300 C (USSR) and syrendivinylbenzencopolymer FK 1621 (GDR). Only by the latter the serotonin intake was significantly reduced with 72.5 +/- 2.0% in comparison with siliconized glas (84.0 +/- 1.5%; p less than 0.001). Precision and analytical sensitivity of the method are high with a variation coefficient of 1.5 to 3.5%.

Subacute effects of propranolol and B 24/76 on isoproterenol-induced rat heart hypertrophy in correlation with blood pressure.

We compared the potential beta-receptor blocker, B 24/76 i.e. 1-(2,4-dichlorophenoxy)-3[2-3,4-dimethoxyphenyl)ethanolamino]-prop an-2-ol, which is characterized by beta 1-adrenoceptor blocking and beta 2-adrenoceptor stimulating properties with propranolol. The studies were performed using an experimental model of isoproterenol-induced heart hypertrophy in rats. A correlation of the blood pressure was neither found in the development nor in the attempt to suppress the development of heart hypertrophy with the two beta-receptor blockers. Both beta-blockers influenced the development of hypertrophy to a different, but not reproducible extent. It was possible to suppress the increased ornithine decarboxylase activity with both beta-blockers in hypertrophied hearts, but there was no effect on the heart mass. Neither propranolol nor B 24/76 could stop the changes in the characteristic myosin isoenzyme pattern of the hypertrophied rat heart. Thus, the investigations did not provide any evidence that the beta-receptor blockers propranolol and B 24/76 have the potency to prevent isoproterenol from producing heart hypertrophy.

[The demonstration of proteolytic activity of bovine coronary arteries and the effect of drugs and other substances on it]. / Zum Nachweis von proteolytischer Aktivität in Rindercoronararterien und deren Beeinflussbarkeit durch Pharmaka und andere Stoffe.

Intracellular neutral proteinases activity of bovine coronary arteries was demonstrated, isolated and partially characterized. The enriched crude enzyme preparation can be inhibited by diisopropylphosphofluoridate (DFP) and phenylmethylsulfonylfluoride (PMSF). The inhibitor concentration (pI50 values) by DFP and PMSF in the enzyme preparation and for trypsin are very similar. Several drugs (isoproterenol, propranolol, theophylline) tested on the enriched crude neutral proteinases preparation showed stimulatory or inhibitory activities. The results are discussed with regard to a possible action mechanism such proteinases on the cyclic AMP/cyclic GMP system.

Expression of isoproterenol-induced activation of protein kinase A in coronary smooth muscle in dependence on homogenization buffer.

The activity of cyclic AMP-dependent protein kinase from the 30,000 x g supernatant fraction of isolated coronary arteries preincubated with either isoproterenol or L-thyroxine was concentration-dependently enhanced by the agonists if the quick-freezed vessels were homogenized at physiological ionic strength of 0.16 M in a buffer containing 20 mM MOPS or 20 mM imidazole. Substitution of phosphate for MOPS or imidazole in the homogenization medium completely abolished the expression of the effects of the hormones unless the ionic strength was increased by addition of 0.25 M NaCl. However, the increase in ionic strength markedly reduced the total activity of the enzyme measured in the presence of 2 x 10(-6) M cyclic AMP indicating a depressive effect of high salt solution. The use of imidazole as the buffer substance at physiological ionic strength likewise reduced the total enzyme activity, whereas the total activities measured after homogenization with MOPS or phosphate buffer at mu = 0.16 were not significantly different.

[Adenosine-3',5'-monophosphate content and muscle tension in isolated coronary arteries under the effect of lanthanum ions]. / Adenosin-3',5'-monophosphat-Gehalt und Muskelspannung isolierter Koronararterien unter der Einwirkung von Lanthan-Ionen.

According to experimental conditions lanthanum ions exert either relaxing or contracting actions on isolated bovine coronary arteries. Both the relaxing and the contracting effect were accompanied by an increase of the cAMP content. The enhancement of the cAMP level could be abolished by diisopropylfluorophosphate (DFP), an inhibitor of adenylate cyclase. The lanthanum-induced relaxation, however, was not influenced neither by DFP nor by the PDE-inhibitor methylisobutylxanthine. It is concluded that cAMP is not involved in the mechanism of La3+-induced relaxation. On La3+-contracted vessels isoprenaline, theophylline, papaverine and trapidil have a spasmolytic action that seems not to be mediated by cAMP.