Activation of ERK and JNK MAP kinases in optic nerves of rats exposed to global cerebral ischemia

OBJECTIVES

To determine the influence of global cerebral ischemia on the activation of extracellular-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK) in optic nerves of rats exposed to different reperfusion periods.

MATERIALS AND METHODS

Transient global cerebral ischemia (20-min duration) was induced by the four-vessel occlusion method. After different reperfusion periods (5 and 10 min; 1; 6 and 12 h after ischemia), optic nerves were extracted and ERK and JNK activation signals were determined by Western immunoblot analyses.

RESULTS

The activation signals of ERK and JNK were detected within first 10 min of reperfusion, but striking activation for both enzymes was found 1 h after ischemia. After a transient decrease, the activation of ERK returned to peak level after 12 h of reperfusion in the second wave of kinase activation. In that period, a slight increase of JNK activation was registered.

CONCLUSION

Our results demonstrated for the first time that ERK and JNK were activated in rat optic nerves during early and later periods of reperfusion, suggesting their potential active role in the response of cerebral white matter tissue to ischemic injury.

NA+, K+-ATPase activity in the brain of the rats with kainic acid-induced seizures: influence of lamotrigine

OBJECTIVE

Kainic acid (KA) is used as an experimental agent which produces convulsions and neurotoxic lesions. Lamotrigine (LTG) is an antiepileptic drug, a glutamate release inhibitor, with action at the neuronal voltage-gated sodium channel. The aim of the present study was to investigate the Na+-K+-ATPase activity in the hippocampus and cortex of rats with KA-induced convulsions. Further, this study was also designed to investigate the influence of the LTG pre-treatment on the mentioned hippocampal and cortex changes.

MATERIALS AND METHODS

The study was carried out on Hannover-Wistar rats. Na+, K+-ATPase activity from hippocampal and temporal cortex tissue was determined two hours after a single subcutaneous KA (8 mg/kg) injection as well as on the third or the fifth experimental day. LTG (30 mg/kg i.p.) was used one hour before KA application and during the next two or four consecutive days. All animals of KA and KA+LTG groups were observed during the first 2 hours after KA application and their behavior was noted. Only animals with characteristically KA-induced behavioral changes observed were used in the study. KA typical behavioral changes were confirmed with electroencephalography.

RESULTS

After KA application, Na+, K+-ATPase activity was significantly inhibited. Na+-K+-ATPase activity inhibition in the hippocampus of the LTG pretreated rats on the fifth experimental day was statistically less pronounced than in KA treated rats. The LTG pretreatment showed also a protective effect on the Na+-K+-ATPase activity in the rats' brain cortex.

CONCLUSION

KA systemic application induced Na+, K+- ATPase activity inhibition in the rat hippocampus and cortex and LTG pre-treatment showed a partially protective effect on the enzyme activity.

Characteristics of blood-pressure control in treated hypertensive patients in Croatia

The aim of our study was to investigate blood pressure (BP) control and different factors with possible influence on BP control in Croatian hypertensive patients. In this cross-sectional investigation, a representative sample of target populations (primary care physicians and patients) from different parts of Croatia was included according to the study protocol. During December 2003 and January 2004, we included, according to correctly completed questionnaires, 141 physicians and 814 hypertensive patients. A controlled BP (BP < 140/90 mmHg) in this hypertensive population treated with antihypertensive drugs was in 23% of patients. The analysis of BP control according to risk factors showed that significantly related with higher levels of systolic or diastolic BP were the age (poorer systolic BP control in patients older than 60 years), left ventricular hypertrophy, changes of the eye retina, smoking and diabetes mellitus. Furthermore, patients from towns closer to the hospital, from urban centers, with higher education and employed had significantly lower average BP. According to our results of hypertension control in Croatia, there is a need and a possibility for the improvement of the quality of hypertension care. The relationship between demographic and cardiovascular risk factors with poor BP control should be taken into account when treating patients.

Effect of indomethacin on motor activity and spinal cord free fatty acid content after experimental spinal cord injury in rabbits

STUDY DESIGN

Determination of functional and biochemical parameters as well as the effect of specific therapies on these parameters, in the experimental model of neurotrauma in rabbits.

OBJECTIVE

To assess the effect of indomethacin (0.1-3.0 mg/kg for 9 days), a potent inhibitor of endogenous prostaglandin synthesis, on the motor activity and on the spinal cord tissue concentration of free palmitic, stearic, oleic, arachidonic and docosahexaenoic acids in an experimental model of a spinal cord injury in rabbits.

SETTING

Faculty of Medicine, University of Rijeka, Croatia.

METHODS

The animals were randomly divided into nine experimental groups, four sham and/or vehicle-treated and five indomethacin-treated (including one sham-operated and four injured groups). Laminectomy was followed by contusion of the spinal cord, using a modification of the technique of Albin. Motor activity was controlled daily during the course of the next nine postoperation days and scored using Tarlov's system. Spinal cord samples from the impact injury site were taken and frozen in liquid nitrogen. Total lipids were isolated and purified by a modification of the method of Folch. Free fatty acids (FFAs) were separated from the total lipid extract by preparative thin-layer chromatography, converted to the corresponding methyl esters and identified using gas chromatography, using nonadecanoic acid as the internal standard.

RESULTS

The concentrations of all analysed free fatty acids were increased in the spinal cord after neurotrauma, in comparison to control tissues. Treatment of injured rabbits with indomethacin resulted in a significant decrease in spinal cord FFAs and exerted a positive effect on neurotrauma-induced motor impairment.

CONCLUSION

These results indicate a mechanism whereby indomethacin protects rabbits from the sequellae of neuronal damage caused by trauma, and suggests that it may be beneficial in the therapy of neurotrauma.

SPONSORSHIP

This work was supported by the Croatian Ministry of Science and Technology (project 062019).

Effects of the hyperbaric oxygen treatment on the Na+,K+ -ATPase and superoxide dismutase activities in the optic nerves of global cerebral ischemia-exposed rats

The effects of hyperbaric oxygen (HBO) treatment on the Na+,K+ -ATPase and superoxide dismutase (SOD) activities were examined in the optic nerves of the rats exposed to global cerebral ischemia. Animals were exposed to global cerebral ischemia of 20-min duration and were either sacrificed or exposed to the first HBO treatment immediately, 0.5, 1, 2, 6, 24, 48, 72 or 168 h after ischemic procedure (for Na+,K+ -ATPase activities measurement) or 2, 24, 48 or 168 h after ischemia (for SOD activities measurement). HBO procedure was repeated for 7 consecutive days. It was found that global cerebral ischemia induced a statistically significant decrease in the Na+,K+ -ATPase activity of the optic nerves, starting from 0.5 to 168 h of reperfusion. Maximal enzymatic inhibition was registered 24 h after the ischemic damage. The decline in the Na+,K+ -ATPase activity was prevented in the animals exposed to HBO treatment within the first 6 h of reperfusion. The results of the presented experiments demonstrated also a statistically significant increase in the SOD activity after 24, 48 and 168 h of reperfusion in the optic nerves of non-HBO-treated ischemic animals as well as in the ischemic animals treated with HBO. Our results indicate that global cerebral ischemia induced a significant alterations in the Na+,K+ -ATPase and SOD activities in the optic nerves during different periods of reperfusion. HBO treatment, started within the first 6 h of reperfusion, prevented ischemia-induced changes in the Na+,K+ -ATPase activity, while the level of the SOD activity in the ischemic animals was not changed after HBO administration.

Hyperbaric oxygen treatment: the influence on the hippocampal superoxide dismutase and Na+,K+-ATPase activities in global cerebral ischemia-exposed rats

The influence of hyperbaric oxygen (HBO) treatment on the activities of superoxide dismutase (SOD) and Na(+),K(+)-ATPase was determined during different time periods of reperfusion in rats exposed to global cerebral ischemia. Ischemic animals were either sacrificed or exposed to the first HBO treatment 2, 24, 48 or 168 h after ischemic insult (for SOD activities measurement) or immediately, 0.5, 1, 2, 6, 24, 48, 72 or 168 h after ischemic procedure (for Na(+),K(+)-ATPase activities measurement). Hyperbaric oxygenation procedure was repeated for seven consecutive days. The results of presented experiments demonstrated the statistically significant increase in the hippocampal SOD activity 24 and 48 h after global cerebral ischemia followed by a decrease in the enzymatic activity 168 h after ischemic insult. In the ischemic rats treated with HBO the level of hippocampal SOD activity was significantly higher after 168 h of reperfusion in comparison to the ischemic, non HBO-treated animals. In addition, it was found that global cerebral ischemia induced a statistically significant decrease of the hippocampal Na(+),K(+)-ATPase activity starting from 1 to 168 h of reperfusion. Maximal enzymatic inhibition was obtained 24 h after the ischemic damage. Decline in Na(+),K(+)-ATPase activity was prevented in the animals exposed to HBO treatment within the first 24 h of reperfusion. Our results suggest that global cerebral ischemia induces significant alterations in the hippocampal SOD and Na(+),K(+)-ATPase activities during different periods of reperfusion. Enhanced SOD activity and preserved Na(+),K(+)-ATPase activity within particular periods of reperfusion, could be indicators of a possible beneficial role of HBO treatment in severe brain ischemia.

Pentylenetetrazol-induced seizures and kindling: changes in free fatty acids, superoxide dismutase, and glutathione peroxidase activity

The whole brain free fatty acid (FFA) level, as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were determined in the frontal cortex, cerebellum, hippocampus, and pons-medulla region of the single pentylenetetrazol (PZT)-treated and PZT-kindled Hannover-Wistar rats. PZT administration in the convulsive dose caused significant increase of the brain FFA content. Decreased SOD activity was detected in the frontal cortex of PZT-kindled rats, whereas decreased GPX activity was found in the frontal cortex and cerebellum of all treated rats, as well as in the hippocampus and pons-medulla of PZT-kindled rats. Kindling caused distinctive change of antioxidative defense in the frontal cortex, hippocampus, and pons-medulla region.

Differential effects of dihydropyridine calcium channel blockers in kainic acid-induced experimental seizures in rats

The anticonvulsant effects of the dihydropyridine calcium channel blockers nifedipine, nicardipine and nimodipine were studied on experimental seizures induced by intra-hippocampal injection of kainic acid (KA) in chloralhydrate anesthetized Wistar rats. The rats were anesthetized and placed in a stereotaxic apparatus. After midline incision four screw electrodes were placed over the left and right frontal and parietal cortex and KA was injected into left dorsal hippocampus via 5-microliter Hamilton microsyringe. The changes in electroencephalograph (EEG) activity and EEG power spectra were recorded in basal conditions and 5, 10, 15, 30 and 60 min following KA injection. KA-induced excitatory changes in the surface EEG activity were associated with the marked increase in EEG power spectra in the frequency range from 14.5-22 Hz. Pretreatment with nifedipine, nicardipine and nimodipine revealed that they exerted certain differences in their anticonvulsant properties. Nimodipine significantly delayed the onset of seizures and prevented the KA-induced changes in EEG and in EEG power spectra in all recorded channels and in a dose dependent manner. Nifedipine exerted significant anticonvulsant effect only in channel four, while nicardipine was ineffective. Our results suggest that anticonvulsant action of some dihydropyridine calcium channel blockers, especially nimodipine may be in part independent of its antagonism on L-type voltage-gated calcium (Ca(2+)) channels.

The influence of MK-801 on the hippocampal free arachidonic acid level and Na+,K+-ATPase activity in global cerebral ischemia-exposed rats

The influence of 20 min global cerebral ischemia on the free arachidonic acid (FAA) level and Na+,K+-ATPase activity in the rat hippocampus at different time points after ischemia was examined. In addition, the effect of MK-801 on mentioned parameters was studied. Animals were exposed to 20 min global cerebral ischemia and were sacrificed immediately, 0.5, 1, 2, 6, 24, 48, 72, and 168 h after ischemic procedure. The level of the FAA and the Na+,K+-ATPase activity was measured during all reperfusion periods examined. Various doses of MK-801 (0.3, 1.0, 3.0, and 5.0 mg/kg) had been injected 30 min before ischemic procedure started. It was found that 20 min global cerebral ischemia induces a statistically significant increase of the FAA level immediately after ischemia and during the first 0.5 h of reperfusion. After a transient decrease, the level of FAA level increased again after 24 and 168 h of recirculation. Treatment with 3.0 mg/kg of MK-801 significantly prevented the FAA accumulation immediately and 0.5 h after ischemic insult while application of 5.0 mg/kg of MK-801 exerted a protective effect during the first 24 h. Global cerebral ischemia induces the significant decline in the Na+,K+-ATPase activity in the hippocampus starting from 1 to 168 h of reperfusion. Maximal inhibition was obtained 24 h after the ischemic damage. Application of 3.0 mg/kg of MK-801 exerted statistically significant protection during the first 24 h while the treatment with 5.0 mg/kg of MK-801 prevented fall in enzymatic activity during all reperfusion periods examined. Our results suggest that, in spite of different and complex pathophysiological mechanisms involved in the increase of FAA level and the decrease of the Na+,K+-ATPase activity, blockade of NMDA receptor subtype provides a very important strategy for the treatment of the postischemic excitotoxicity.

Altered activities of rat brain metabolic enzymes caused by pentylenetetrazol kindling and pentylenetetrazol--induced seizures

The aim of our study was to investigate amino acid and energy metabolism of pentylenetetrazol (PTZ)-kindled animals. Glutamate dehydrogenase, aspartate-aminotransferase (AST), alanine-aminotransferase, gamma-glutamyltransferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and creatine kinase (CK) were determined in the frontal cortex, cerebellum, hippocampus and pons-medulla regions of Hannover-Wistar rats. The rats were randomly divided into four experimental groups: (a) control; (b) rats which received a single PTZ injection in a subconvulsive dose of 40 mg/kg i.p.; (c) rats which received a single PTZ injection in a convulsive dose of 50 mg/kg i.p.; and (d) PTZ-kindled rats. Kindling increased ALP activity throughout the brain, elevated AST as well as LDH activity in the frontal cortex and hippocampus and decreased CK activity in the frontal cortex and cerebellum. Acute seizures of the same intensity did not induce these alterations. The observed effects therefore are obviously linked to the kindling phenomenon and not to seizure activity. Changes appeared mainly in the frontal cortex and hippocampus, i.e. brain areas believed to be directly involved in kindling.

Electroconvulsive shock in rats: changes in superoxide dismutase and glutathione peroxidase activity

Seizures trigger a variety of biochemical processes including an influx of extracellular Ca(2+), activation of membrane phospholipases, liberation of free fatty acids, diacylglycerols, eicosanoids, lipid peroxides and free radicals. These lipid metabolites along with abnormal ion homeostasis may be involved in cell injury and cell death. The aim of this study was to determine brain antioxidant enzyme activities in rats with electroconvulsive shock (ECS)-induced seizures. ECS, single or repeated, induced a decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities in various brain regions. The most prominent changes of enzymatic activities were observed in rats that received five ECSs with 24-h recovery period between them. Decreased SOD activity was observed in the frontal cortex of all treated animals except those sacrificed 24 h after single ECS, in the cerebellum of the animals that received repeated ECSs, in the hippocampus of animals that were decapitated 2 h after a single ECS and in the pons-medulla region of rats that received five daily ECSs. Decreased GPX activity was found in all examined brain regions of the rats that received five ECSs, the cortex and hippocampus of rats that were decapitated 2 h after single ECS and the cortex of those that received 10 ECSs with 48 h between them. The results show that neither 24-h nor 48-h recovery period was sufficient for the normalisation of antioxidative enzyme activities after repeated ECS treatment.

Lithium plus pilocarpine induced status epilepticus--biochemical changes

The aim of the study was to investigate the changes in biochemical mechanisms facilitating cellular damages in the lithium plus pilocarpine treatment and the resulting status epilepticus. The whole brain free fatty acid (FFA) level as well as the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), glutamate dehydrogenase, aspartate-aminotransferase (AST), alanine-aminotransferase, gamma-glutamoyl transferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and creatine kinase in the frontal cortex, cerebellum, hippocampus and pons-medulla region of Hannover-Wistar rats were determined. The control group was intact with no previous experimental history. LiCl (125 mg/kg i.p.) was injected 20 h prior to pilocarpine (30 mg/kg i.p.) and the treated rats were sacrificed 1 or 2 1/2 h after pilocarpine administration. The results show that lithium plus pilocarpine administration and the resulting status epilepticus produced the significant increase of the brain FFA content. Decreased GPX activities were detected in the frontal cortex, cerebellum and hippocampus of the treated rats without the accompanying decrease of SOD activity. Increased AST and LDH activities were observed in the frontal cortex, increased soluble ALP activities in the frontal cortex and pons-medulla region whereas the increased activity of membrane bound ALP was detected in the hippocampus of the rats with status epilepticus. Activities of the other analysed enzymes did not change in the examined brain regions. The presented data indicate clear regional differences of biochemical changes caused by lithium plus pilocarpine treatment and the resulting status epilepticus, frontal cortex being the most affected site.

The influence of nimodipine, nicardipine and amlodipine on the brain free fatty acid level in rats with penicillin-induced seizures

1. The aim of this study was to investigate the effects of the calcium channel blockers, nimodipine, nicardipine and amlodipine, on the brain free fatty acid (FFA) level in rats with chemically-induced seizures. 2. The study was carried out on Hannover-Wistar rats. Animals were anesthetized and placed in a stereotaxic apparatus. Each of them received an injection of penicillin (5000 IU/5 microliters) into the left lateral ventricle (i.c.v.). Various doses (1, 3, 10 or 30 mg/kg) of nimodipine, nicardipine or amlodipine had been injected i.p. 30 min before the penicillin application. The rats were decapitated 5 min after the occurrence of epileptic seizures. FFAs were quantified by gas chromatography using the internal standard method. 3. The results demonstrate that i.c.v. injection of penicillin was associated with significant increase in the brain FFA concentration. Tested doses of nicardipine and amlodipine did not influence the increase of the brain free palmitic, stearic, oleic and arachidonic acid level while nimodipine prevented the accumulation of free palmitic, oleic and arachidonic acid in rats with penicillin-induced seizures. Statistically insignificant decrease of steric acid was observed in animals pretreated with nimodipine. 4. It maybe assumed that the brain FFA accumulation caused by i.c.v. penicillin administration is not predominantly associated with a disturbance in calcium homeostasis via L-type voltage-sensitive calcium channels, but by some other membrane and/or intracellular mechanisms.

Education in clinical pharmacology at the Rijeka School of Medicine, Croatia

OBJECTIVE

Irrational drug prescribing is a global problem that exists both in developed and developing countries. Education is the key to improved effectiveness and safety in drug therapy. Development of clinical pharmacology (CP) as an independent discipline at the Rijeka School of Medicine has been slow and unsatisfactory. It was taken only as a part of some postgraduate courses. In the 1995/1996 academic year clinical pharmacology was offered for the first time to sixth year medical students as a non-mandatory subject. The purpose of this study was to emphasize the importance of education in clinical pharmacology at the Rijeka School of Medicine.

METHODS

This survey was an uncontrolled study based on responses to questionnaires and a test consisting of written patient problems given to sixth year medical students and to general practitioners who were following a course in clinical pharmacology.

RESULTS

The results of the questionnaire showed that both undergraduate and postgraduate students consider that they are not being adequately trained to prescribe drugs rationally and that they believe that clinical pharmacology should become a mandatory subject in the undergraduate medical curriculum. The results of the written patient problem test support this. Both groups of students demonstrated greater skills in solving the diagnostic part than the therapeutic part of the test. A great improvement in the students' ability to solve the therapeutic part was observed after they had completed the CP course.

CONCLUSION

The results of this survey underline the necessity of education in clinical pharmacology.

The influence of nicardipine and ifenprodil on the brain free arachidonic acid level and behavior in hypoxia-exposed rats

1. The effects of the calcium channel blockers, nicardipine and ifenprodil, on the brain free arachidonic acid level and learning ability in rats exposed to hypoxia were examined. 2. Adult rats were injected with 0.003; 0.01; 0.03; 0.1; 0.3 or 1.0 mg/kg of tested drugs i.p. Thirty min later the learning ability was tested in a passive avoidance task according to the step-through procedure. Immediately after the training trial, the animals were subjected to a period of oxygen deprivation hypoxia until the loss of the righting reflex. The retention trial was carried out 24 hr later. 3. The other groups of animals were pretreated with mentioned substances before hypoxia-exposure. Fifteen min after the loss of the righting reflex they were decapitated and brains were frozen in liquid nitrogen. The brain free arachidonic acid level was quantified by gas chromatography. 4. Both nicardipine and ifenprodil were effective in preventing a memory decline in hypoxia-exposed rats but did not prevent the accumulation of the brain free arachidonic acid in hypoxia-exposed rats. 5. The protective effects of both substances in behavioral studies during acute brain damage caused by hypoxia could not be explained by the prevention of the increase of the brain free arachidonic acid, but by some other mechanism.

The influence of nimodipine and MK-801 on the brain free arachidonic acid level and the learning ability in hypoxia-exposed rats

1. The influence of voltage dependent calcium channel blocker (VDCC), nimodipine and N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 on the brain free arachidonic acid (FAA) level and on the learning ability in hypoxia-exposed rats was examined. 2. Some animals were decapitated after cerebral hypoxia had been obtained and the brain FAA level was determined by gas chromatography. The other animals were trained in a passive avoidance procedure and were exposed to hypoxic conditions immediately after the learning trial response had been acquired. A passive avoidance retention test was performed 24 hours later. 3. Various doses of nimodipine (0.03; 0.1; 0.3 and 1.0 mg/kg) and MK-801 (0.03; 0.1 and 0.3 mg/kg) had been injected 30 minutes before biochemical or behavioral procedures started. 4. It was found that hypoxia strongly increased the brain FAA level and impaired the retention of the passive avoidance response. 5. Pretreatment with 0.3 mg/kg and 1.0 mg/kg of nimodipine prevented the brain FAA accumulation. It has also been shown that all tested doses of nimodipine significantly improved the retention deficit in the animals exposed to hypoxia. 6. Neither the one of tested doses of MK-801 influenced significantly the increase of the brain FAA level and/or passive avoidance behavior in hypoxic animals. 7. These results confirm the hypothesis that the brain FAA accumulation and cognitive impairment, caused by hypoxia, are maybe associated with disturbances in calcium homeostasis and that nimodipine may be useful in ameliorating the hypoxia-induced brain tissue damage. Blocade of NMDA receptor-channel complex by MK-801 was not sufficient to prevent hypoxia-induced neuronal damage.

Effects of nimodipine, felodipine and amlodipine on electroconvulsive shock-induced amnesia in the rat

The effects of various doses (0.03, 0.1, 0.3 or 1.0 mg/kg) of the Ca2+ channel blockers nimodipine, felodipine and amlodipine on the learning ability of rats exposed to electroconvulsive shock were examined. The animals were trained in a passive avoidance procedure. The drugs tested were injected 30 min before the learning trial started. The electroconvulsive shock was given immediately after the learning trial response had been acquired. A passive avoidance retention test was performed 24 h later. It was found that electroconvulsive shock strongly impaired the retention of the passive avoidance response. Nimodipine, felodipine and amlodipine did not influence the passive avoidance behavior in the sham electroconvulsive shock group, but significantly improved the retention deficits in the animals exposed to electroconvulsive shock. These findings support the hypothesis that perturbations in Ca2+ homeostasis can contribute to the memory deficits associated with electroconvulsive shock. The antiamnestic effects of the substances tested make them interesting candidates for clinical trials in patients with cognitive impairment caused by electroconvulsive shock therapy.

Effects of nicardipine, felodipine and nifedipine on passive avoidance behavior of intact and hypoxia-exposed rats

The effects of various doses (0.03, 0.1, 0.3 or 1 mg/kg) of the calcium channel blockers nicardipine, felodipine and nifedipine on the learning ability in intact rats and on hypoxia-induced retention deficits were examined. All animals were trained in a passive avoidance procedure. The drugs tested had been injected 30 minutes before the learning trial started. Some animals were exposed to a hypoxic condition immediately after the learning trial response had been acquired. A passive avoidance retention test was performed 24 hours later. It was found that hypoxia strongly impaired the retention of the passive avoidance response. Nicardipine, felodipine and nifedipine did not influence the passive avoidance behavior in the intact animals, but significantly improved the retention deficits in the animals exposed to hypoxia. The effects of the substances tested were dose-dependent. These findings support the hypothesis that perturbations in calcium homeostasis can contribute to the memory deficits associated with hypoxic conditions.

Clinical pharmacology in Eastern European countries

The current status of clinical pharmacology (CP) in the countries of the former Eastern block is presented. The difficulties in obtaining an accurate comparative view are pointed out. CP is unevenly developed in Eastern European countries and the number of hours devoted to basic/clinical pharmacology differs considerably 100/nil to 240/50. The same is true for the orientation of clinical pharmacology, where present. It is mainly basic in only a few countries (Rumania, Turkey, some parts of the former Yugoslavia) and mainly clinical in Czecho-Slovakia, Croatia, Hungary, Poland, Greece. The number of CP units and CP specialists varies greatly as well (from none to more than 10 per country). The awareness that CP, in many countries is still young and the branch of (clinical) medicine is of great importance, not only for rational pharmacotherapy but also for other services as well, education and research is growing. In spite of the fact that the present status of CP in Eastern European countries is generally unsatisfactory, there are realistic chances that in the (near?) future, CP will develop to match the activities now present in the more developed countries.

Influence of various cholinergic and anticholinergic drugs on rectal temperature in rats

The influence of various cholinergic drugs on rectal temperature of rats under controlled laboratory conditions was examined. Animals were anaesthetized by intraperitoneal injection of thiopental. Three hours later acetylcholine, methacholine, arecoline, nicotine, neostigmine, atropine, methylatropine, mecamylamine or hemicholinium were injected intrahypothalamically (i.h.), intracerebroventricularly (i.c.v.) or intraperitoneally (i.p.). Rectal temperature was measured at 15 min-intervals for 1 hr after the substances were injected. Our results indicate that the cholinergic mechanisms play an important role in thermoregulatory processes in rats. Cholinergic activation decreases rectal temperature, due to an increased activity of central, and not of peripheral cholinergic neurotransmission. The hypothermic effect of cholinomimetics is mediated through an activation of muscarinic cholinergic receptors.

Effect of piracetam on motor activity of spinal cord injured rabbits

Experimental, lumbal spinal cord compact injury provoked by a strike of 71 p.cm caused a spontaneously irreversible paraplegy in rabbits. Motor activity of injured rabbits was controlled during nine posttraumatic days. Piracetam significantly reduced motor dysfunction of the hind legs. Piracetam (2 g.kg-1) was given i.v., once per day during nine posttraumatic days. The beneficial effect of piracetam was more pronounced when the delay between trauma and the onset of drug administration was shorter. When this delay amounted to 360 minutes, piracetam did not influence significantly motor activity of contusioned animals. No side effects of piracetam were observed.

[The importance of histaminergic H1 and H2 receptors for the contractile effect of histamine on human umbilical veins]

Influence of histamine and histaminergic H1 blockers (antazoline, promethazine) and H2 blockers (cimetidine, ranitidine) on isometric contraction of helically cut strips of human umbilical vein was examined. Histamine produced dose-related contraction of the vein strip, while histaminergic H1 and H2 blockers did not changed the tonus of the vein. The contractile activity of histamine was not influenced by cimetidine or ranitidine, while antazoline and promethazine antagonized mentioned activity of histamine completely. We suppose that histamine exerts contractile effect of human umbilical vein by acting on H1 receptors while H2 receptors are not involved in the mentioned activity of histamine.