Effect of sulodexide on vascular responses and liver mitochondrial function in diabetic rats.

This study investigates the effects of long-term treatment with sulodexide (SLX) on norepinephrine (NE)-induced contractions, acetylcholine(Ach)-induced relaxations, acute cyclooxygenase blockade by diclofenac (DIC) in isolated femoral arteries (FA) and the parameters of oxidative phosporylation in liver mitochondria. 15-weeks old Wistar rats were divided into four groups: control (C; injected with saline solution), treated control (C+SLX), diabetic (DM) and treated diabetic (DM+SLX). Diabetes was induced with a single i.v. dose of streptozotocin (STZ) 45 mg.kg(-1). SLX was administered i.p., at dose 100 IU.kg(-1) daily for 5 weeks. Vascular responses of isolated femoral arteries were measured using Mulvany-Halpern myograph. Respiratory function of the mitochondria was determined using voltamperometric method on oxygraph Gilson. In diabetic rats the amplitude of maximal response to NE was elevated. DIC pretreatment decreased the amplitudes of NE-induced contractions in all groups of rats. SLX treatment decreased sensitivity of FA to NE and caused higher relaxatory responses to Ach in C and DM. Oxygen consumption and phosphorylation rates ([QO(2)(S(3))], [QO(2)(S(4))] and (OPR)) and respiratory control ratio (RCR) were decreased in the mitochondria of DM rats. Mitochondria of C rats were not affected with SLX treatment. Administration of SLX in DM rats was associated with increase of RCR, other parameters were not affected. Our findings suggest that SLX treatment might be associated with vasculoprotective effects during diabetes and improvement of mitochondrial function.

Vascular reactivity of arteria femoralis in adult and aged spontaneously hypertensive and Wistar-Kyoto rats.

AIM: The relationship of age and hypertension on endothelial dysfunction and increased responses to vasoconstrictor stimuli. BACKGROUND: Hypertension is a disease accompanied by endothelial dysfunction and is characterized by an impaired vascular reactivity and enhanced activity of sympathetic nervous system. MATERIALS AND METHODS: In our experiment, we used spontaneously hypertensive rats representing model of essential hypertension and the Wistar-Kyoto rats as normotensive strain. Femoral arteries of adult and aged rats were put into the chamber of Mulvany-Halpern isometric myograph. As the nutrient solution, the modified Krebs-Henseleit solution having temperature 37 °C and bubbled with O2 was used. After 30 minutes stabilization of blood vessels, a dose-dependent curve of norepinephrine response was recorded (concentrations 3x10-8 M, 10-7 M, 3x10-7 M, 10-6 M, 3x10-6 M, 10-5 M, 3x10-5 M, 10-4 M), followed by a dose-dependent curve of acetylcholine response (concentrations 3x10-8 M, 10-7 M, 3x10-7 M, 10-6 M, 3x10-6 M). RESULTS: Our experiments recorded an increased reactivity to contraction stimuli in spontaneously hypertensive animals. Vascular reactivity to norepinephrine at 5 month and 12 month old rats from the same group was not significantly affected. Our experiments on the other hand, did not record a reduced endothelium-dependent relaxation in hypertensive compared to normotensive animals, neither in different age groups. CONCLUSIONS: Increased norepinephrine-induced contraction occurs even before development of reduced acetylcholine-induced relaxation in SHR rats. We predict that in our experiment hypertension plays a bigger role in the development of endothelial dysfunction than aging (Fig. 2, Ref. 22).

Biochemical evaluation of the antiplatelet effect of aspirin in patients at different levels of cardiovascular risk.

BACKGROUND: The phenomenon called aspirin resistance is being intensively discussed. METHODS: To evaluate the biochemical aspirin response, the method of urinary 11-dehydro TXB2 levels measurement was used. Quantitative detection of TXB2 in urine was determined by competitive enzyme immunoassay, using human Thromboxane B2 ELISA-kit. We investigated the urine samples from 69 patients. RESULTS: The mean urinary levels of 11-dehydro TXB2 were significantly lower in patients in the primary and secondary types of aspirin prevention comparing with the control group of patients not taking aspirin. The difference in thromboxane concentrations between the two groups of patients taking aspirin did not reach statistical significance. Our results did not show significant differences in the biochemically measured aspirin response when comparing diabetics with non-diabetics. Similarly, the observed tendency to higher thromboxane levels in women did not show to be significantly different from men. CONCLUSION: Our pilot study did not show any significant differences among patients at different cardiovascular risk. Since there is currently no standard laboratory method to detect aspirin non-responders available, the term aspirin resistance remains controversial and requires further research. Every effort should be done to improve patients' compliance and to prevent clinically relevant interactions of aspirin with ibuprofen. The elimination of these two factors as was the case in our study may provide better efficacy of the antithrombotic prevention by aspirin (Fig. 2, Tab. 4, Ref. 19). Full Text (Free, PDF) www.bmj.sk.

Sulodexide improves endothelial dysfunction in streptozotocin-induced diabetes in rats.

Diabetes mellitus is associated with many complications including retinopathy, nephropathy, neuropathy and angiopathy. Increased cardiovascular risk is accompanied with diabetes-induced endothelial dysfunction. Pharmacological agents with endothelium-protective effects may decrease cardiovascular complications. In present study sulodexide (glycosaminoglycans composed from heparin-like and dermatan fractions) was chosen to evaluate its protective properties on endothelial dysfunction in diabetes. Effect of sulodexide treatment (SLX, 100 UI/kg/day, i.p.) in 5 and 10 weeks lasting streptozotocin-induced diabetes (30 mg/kg/day, i.p. administered for three consecutive days) was investigated. Animals were divided into four groups: control (injected with saline solution), control-treated with sulodexide (SLX), diabetic (DM) and diabetic-treated with sulodexide (DM+SLX). The pre-prandial and postprandial plasma glucose levels, number of circulating endothelial cells (EC) and acetylcholine-induced relaxation of isolated aorta and mesenteric artery were evaluated. Streptozotocin elicited hyperglycemia irrespective of SLX treatment. Streptozotocin-induced diabetes enhanced the number of circulating endothelial cells compared to controls. SLX treatment decreased the number of EC in 10-week diabetes. Acetylcholine-induced relaxation of mesenteric arteries was significantly impaired in 5 and 10-week diabetes. SLX administration improved relaxation to acetylcholine in 5 and 10-week diabetes. Diabetes impaired acetylcholine-induced relaxation of rat aorta irrespective of SLX treatment. Our results demonstrate that SLX treatment lowers the number of circulating endothelial cells and improves endothelium-dependent relaxation in small arteries. These findings suggest endothelium-protective effect of sulodexide in streptozotocin-induced diabetes.

Mathematical model indicates nonlinearity of noradrenaline effect on rat renal artery.

The aim of this work is to present the efficacy of a previously introduced computational procedure, developed for evaluation of vascular responsiveness. On this reason, as an example a common study of noradrenaline (NA) effect on a rat renal artery under in vitro conditions was arbitrarily selected. The response of the arterial segment to NA doses (0.1-10 microg) was digitally recorded on a PC and employed to develop mathematical model of NA effect. Using the model, the following NA effect variables were determined: the vessel sensitivity parameter, mean effect time and rate constant, respectively, characterizing the effect intensity, duration, and regression and also classic response variables: the maximal effect and time of the maximal effect. The two-way analysis of variance followed by Bonferroni's test revealed a significant influence of the increasing NA dose on the vessel sensitivity parameter and mean effect time. These findings indicated nonlinearity of processes underlying NA effect on the rat renal artery over the given range of NA doses. The procedure exemplified has the potential for use as an effective adjunct to routine studies of vascular responsiveness as it enables the extraction of meaningful information which cannot by obtained by common manual evaluation procedures.

Endothelaemia--a marker of vascular damage.

OBJECTIVES: The aim of the study was to determine the amount of circulating endothelial cells (CECs) in patients with an advanced cardiovascular (CV) disease, compare the values with a control group and finally to ascertain if there are statistically significant differences within the studied patient groups. BACKGROUND: Endothelaemia has been intensively studied as a marker of vascular injury. Clinical studies have demonstrated an increased endothelaemia in patients at high CV risk but also in certain non-cardiovascular disorders. Its possible usage in the diagnostics of the acute coronary syndrome and for CV risk assessment needs further investigations. METHODS: Thirty six hospitalized patients were studied. Quantitative measurement of endothelaemia was performed by the method developed by J. Hladovec. It is based on ECs counting in Bürker's chamber after their isolation with platelets and the removal of the latter by an addition of adenosine-diphosphate. RESULTS: The mean baseline endothelaemia was significantly higher in patients with increased cardiovascular risk when compared with the control group (1.38 +/- 0.899): ACS (4.9 +/- 1.59, p < 0.05) and PAOD (3.74 +/- 0.61, p < 0.05). When comparing the mean endothelaemia values in patients with PAOD before (2.67 +/- 0.86) and after (3.88 +/- 0.77) surgery, a significant increase of endothelaemia was observed (p < 0.05). CONCLUSION: Our pilot study, though limited by a relatively small number of patients, proved a significant increase of endothelaemia in patients at high CV risk, which is consistent with other available data. The introduction of newer specific methods based on immunomagnetic principles may provide a wider use of endothelaemia measurement in clinical settings (Fig. 3, Ref. 17). Full Text (Free, PDF) www.bmj.sk.

Experience with problem oriented teaching in pharmacology.

Pharmacology is one of the core subjects for further graduation in both preclinical and clinical area. Medical education is being performed either in the "classical" way (lecture based learning--LBL) or in a more advanced form, such as problem based learning (PBL). According to the Medline database, the interest in PBL is still increasing. At our department, the PBL has been introduced using the knowledge obtained at the the Mac Master University and University of Groningen. PBL in pharmacology requires well-qualified staff with clinical experience. A common character of PBL is the use of selected clinical cases as models and starting points to study certain topics with a student centred approach. In an interview we made on a sample of 88 students of our medical faculty in the last study year, 65.5% of them found the amount of information concerning pharmacotherapy not sufficient for their future clinical practice and 83.3% did not feel able to use the knowledge obtained. More than 90% of students did not see enough opportunities for pharmacotherapy training during clinical subject courses. These results are in support of our orientation of teaching towards the PBL. This type of teaching forces students to be active, trains their skills in communication and selection of knowledge, which is believed to enhance the long-term knowledge retention. By using the hybrid PBL-LBL model at our department we respect the principal proposal of medical education and attempt to improve skills in decision making in training of future medical doctors. (Tab. 3, Fig. 2, Ref. 13.)

The Slovak Drug Information (Druginfo) Centre during the period 1997-2004.

OBJECTIVES: The aim of the presented study was to evaluate the profile of users, the number and character of questions which were received during the period May 1997-December 2004. BACKGROUND: The drug information centre (Druginfo) has been established in Slovak Republic at the Department of Pharmacology in May 1997. Since 2002 Druginfo is a member of International Register of Drug Information Services of the Society of Hospital Pharmacists of Australia. Druginfo provides voluntarily free of charge drug information for healthcare professionals. METHOD: Druginfo receives questions addressed via phone, fax and e-mail. The questions were replied by consulting pharmacologists on duty. The data for this study were obtained from records which include list the received questions and the basic information about the questioners. RESULTS: The Druginfo received 495 questions during the period May 1997-December 2004. Questions were mostly from hospital physicians, followed by outpatient physicians and employees of the Faculty of Medicine. The most frequent specializations of the asking physicians were internal medicine, gynaecology-obstetrics, clinical pharmacology and general medicine. The most common topic was basic information about drugs, followed by questions concerning the use of drugs in pregnancy and lactation. According to the ATC classification the questions were most often related to antiinfective drugs, cardiovascular drugs and psychiatric drugs. CONCLUSION: The existence of Druginfo in Slovak Republic represents a possibility of an open access to independent drug information. (Fig. 3, Ref. 11.)

The effect of meloxicam and deendothelisation on vascular responses in the rabbit renal and ear arteries.

BACKGROUND: The use of non-steroidal anti-inflammatory drugs (NSAIDs) is frequently limited by adverse effects resulting from the disruption of homeostatic functions of prostaglandins. OBJECTIVES: This study was aimed at the evaluation of the effect of selective COX-2 inhibitor meloxicam on vasoconstrictor responses to noradrenaline (NA) in rabbit renal artery chosen as a model vessel and in rabbit ear artery as a peripheral artery under in vitro conditions. METHODS: Rabbit renal and ear arteries were perfused at constant flow. Vascular responses to NA before and after meloxicam administration and after deendothelisation by air bubbles were measured and registered as changes in perfusion pressure. RESULTS: It was found out that vasoconstrictor responses to noradrenaline when exposed to meloxicam were not enhanced significantly in both arterial preparations. Deendothelisation itself did not increase responses affected by meloxicam in the renal and ear arteries but in comparison with control groups the responses were significantly augmented, especially in the ear artery. CONCLUSIONS: The results obtained in this study demonstrate that meloxicam had not affected adversely the vasoconstrictor activity in different types of vessels without selectivity on vascular beds. Endothelial removal potentiated vasoconstrictor responses in arteries pre-treated by meloxicam when compared with intact vessels. (Tab. 2, Fig. 4, Ref. 19.)

Computer-based methods for measurement, recording and modeling vessel responses in vitro: a pilot study with noradrenaline.

This paper reports the first results of an ongoing methodological pilot study aimed at designing techniques for the automatic measurement and digital recording of vessel responses to biologically active substances under in vitro conditions and for the mathematical modeling of the underlying processes. The techniques presented in this pilot study allowed us to determine model-based estimates of the parameters characterizing vasoconstrictor responses, i.e., the vessel sensitivity parameter, the mean time of vasoconstrictor response and the rate constant of vessel relaxation. The given parameters are not dependent on doses of biologically active substances, provided that the underlying processes satisfy the principle of superposition. Use of these techniques is shown in the classic study of vasoconstrictor responses to noradrenaline in the rat renal artery.

Effect of indomethacin and deendothelisation on vascular responses in the renal artery.

Vasodilator prostaglandins (PGE2, PGI2) play an important role in the regulation of renal blood flow. Hence, inhibition of their production with nonsteroidal anti-inflammatory drugs increases renal vascular resistance and exerts adverse renal effects. It has been reported that besides endothelium-derived prostaglandin products, nitric oxide (NO) may be mainly involved in regulation of renal functions. The aim of our study was to evaluate the effect of cyclooxygenase inhibition with indomethacin and endothelium removal on vascular responses of the renal artery as a model vessel. Isolated segments of rabbit renal arteries were perfused at constant flow. Indomethacin administration (10(-5) mol x l(-1)) significantly increased the responses to single doses (0.1, 1, 10 microg) of noradrenaline (NA) as compared with the controls. In indomethacin-pretreated vessels, subsequent deendothelisation by air bubbles enhanced the constrictor responses to NA. In reversed order, when deendothelisation was followed by indomethacin administration, the responses to NA were similar in character. A comparison of renal artery responses to NA in both experimental situations did not reveal any significant differences. It can be supposed that endothelial and non-endothelial factors may be involved in local regulation of renal vascular tone.