Miriam Petrová

Ca2+ sensitization and Ca2+ entry in the control of blood pressure and adrenergic vasoconstriction in conscious Wistar-Kyoto and spontaneously hypertensive rats.

Background: Calcium entry through nifedipine-sensitive L-type voltage-dependent calcium channels (L-VDCC) is augmented in spontaneously hypertensive rats (SHR) characterized by enhanced sympathetic vasoconstriction. However, the changes of calcium sensitization mediated by RhoA/Rho kinase pathway are less understood. Methods and results: The participation of calcium entry and calcium sensitization in the control of blood pressure (BP) and vascular contraction was studied in SHR and normotensive Wistar–Kyoto (WKY) rats. The acute administration of fasudil (Rho kinase inhibitor) caused BP decrease which lasted longer in SHR. Fasudil also attenuated adrenergic contraction in femoral or mesenteric arteries of WKY and SHR. BP reduction elicited by fasudil in WKY was more pronounced than that induced by L-VDCC blocker nifedipine (−33 ± 2 vs. −15 ± 3% of baseline BP, P < 0.001), whereas both inhibitors were similarly effective in SHR (−36 ± 4 vs. −41 ± 2%). Fasudil pretreatment also attenuated BP elevation elicited by L-VDCC agonist BAY K8644 more in WKY than in SHR (−63 ± 4 vs. −42 ± 5%, P < 0.001), indicating reduced calcium sensitization in SHR. Moreover, fasudil pretreatment shifted norepinephrine dose–response curves to the right more in WKY than in SHR. The additional nifedipine pretreatment shifted these curves further to the right but this shift was more pronounced in SHR than in WKY. Thus adrenergic vasoconstriction is more dependent on L-VDCC in SHR and on RhoA/Rho kinase pathway in WKY rats. Conclusion: Ca2+ sensitization mediated by RhoA/Rho kinase pathway is attenuated in SHR compared with normotensive WKY rats. This might be a part of the compensation for enhanced Ca2+ entry through L-VDCC in genetic hypertension.

Influence of calcium-dependent potassium channel blockade and nitric oxide inhibition on norepinephrine-induced contractions in two forms of genetic hypertension

The activation of Ca(2+)-dependent K(+) channels (BK(Ca)) leads to the attenuation of vascular contraction. Our study aimed to evaluate BK(Ca) influence on norepinephrine (NE)-induced femoral artery contraction in two forms of genetic hypertension. NE dose-response curves were studied before and after BK(Ca) blockade or after combined blockade of BK(Ca) and NO synthase (NOS) in femoral arteries with intact endothelium from normotensive Wistar (WIS), hypertensive hereditary hypertriglyceridemic (HTG), or spontaneously hypertensive rats (SHR). NE-induced contractions of femoral arteries were augmented in both hypertensive strains compared with Wistar rats, but acetylcholine-induced relaxation was impaired in HTG only. The increase of basal vascular tone of isolated arteries after BK(Ca) blockade was similar in all rat strains, but subsequent NOS inhibition increased basal vascular tone more in vessels from both hypertensive rat strains. NOS inhibition increased sensitivity to NE in all strains, but BK(Ca) blockade in SHR only. Neither treatment enhanced maximal NE-induced contraction. NO-dependent attenuation of NE-induced contractions was greater in SHR than HTG or Wistar vessels, whereas large conductance Ca(2+)-dependent K(+) channels may play a greater role in modulating vascular contraction in the severe form of hypertension.

Analysis of non-steroidal anti-inflammatory drug use in hospitalized patients and perception of their risk

ABSTRACT Non-steroidal anti-inflammatory drugs (NSAIDs) belong to the most widely prescribed and used pharmacological agents worldwide. Data gathered in the last decade show increased incidence of thrombotic events during NSAID administration. Analysis of NSAID usage and assessment of risk for development of cardiovascular adverse effects is needed for improving patient safety. For limiting the impact of adverse effects on the health of patients, NSAID users should be informed about the possible adverse effects and their symptoms to ensure early detection and treatment discontinuation. In the presented study, we retrospectively analyzed the administration of NSAIDs in a group of patients (n=428) in need of analgesic treatment hospitalized at a department of internal medicine. Factors increasing the risk for cardiovascular adverse effects were also investigated. A separate questionnaire study was conducted to gather information concerning the knowledge of hospitalized NSAID users (n=251) about adverse effects of the medication used. For purpose of comparison, we conducted a similar study in a group of 234 random respondents from a shopping center. Data were evaluated using descriptive statistics, Student´s t-test and chi-squared test. Our results suggest that the majority of patients treated with NSAIDs have factors indicating increased risk of development of adverse effects, most commonly arterial hypertension (58.2% of patients). The results of our questionnaire study show limited knowledge of NSAID users about the risk of the therapy. Nearly half of the respondents were unaware of any adverse effects. We consider as alarming that only a limited number of respondents were informed by their physician or pharmacist about the possible risks of treatment. In conclusion, we found that hospitalized NSAID users often have a history of diseases predisposing to the development of cardiovascular adverse effects of NSAIDs. Despite this, their knowledge about the risk of treatment is insufficient.

Contribution of Ca²⁺-dependent Cl⁻ channels to norepinephrine-induced contraction of femoral artery is replaced by increasing EDCF contribution during ageing.

The activation of Ca2+-dependent Cl− channels during norepinephrine-induced contraction of vascular smooth muscle was suggested to depolarize cell membrane and to increase Ca2+ entry. Hypertension and ageing are associated with altered Ca2+ handling including possible activation of Ca2+-dependent Cl− channels. Our study was aimed to determine Ca2+-dependent Cl− channels contribution to norepinephrine-induced contraction during hypertension and ageing. Norepinephrine-induced concentration-response curves of femoral arteries from 6- and 12-month-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were recorded using wire myograph. Pretreatment with Ca2+-dependent Cl- channel inhibitor indanyloxyacetic acid 94 [R(+)-IAA-94](IAA) attenuated norepinephrine-induced contraction in all groups, but relatively more in WKY than SHR arteries. The attenuation of norepinephrine-induced contraction after Ca2+-dependent Cl− channels blockade was partially reduced in 12-month-old WKY rats, but substantially diminished in 12-month-old SHR. IAA effect was enhanced after NO synthase inhibition but decreased by ageing. In 20-month-old WKY rats norepinephrine-induced contraction was not affected by IAA but was almost abolished after cyclooxygenase inhibition by indomethacin or niflumic acid. In conclusion, contribution of Ca2+-dependent Cl− channels to norepinephrine-induced contraction diminished with age, hypertension development, and/or NO synthesis inhibition. Ca2+-dependent Cl− channels are important for maintenance of normal vascular tone while their inactivation/closing might be a pathological mechanism.

Long-term Treatment with Hesperidin Improves Endothelium-dependent Vasodilation in Femoral Artery of Spontaneously Hypertensive Rats: The Involvement of NO-synthase and Kv Channels.

Hesperidin is the most common flavonoid found in citrus fruits and is expected to exert vasodilation action relevant to its health benefits. The present study aimed to explore the effect of hesperidin on the vascular responses in normotensive and hypertensive rats and the involvement of NO‐synthase and Kv channels. The 15‐week‐old Wistar and spontaneously hypertensive rats (SHR) were randomized to orally receive either hesperidin (50 mg/kg/day) or a corresponding volume of the water for 4 weeks. Vascular responses of isolated femoral arteries were studied with myograph in control conditions and during inhibition of NO‐synthase with l‐NNA and Kv channels with 4‐AP. Hesperidin had no effect on blood pressure. Endothelium‐dependent vasodilation in Wistar and SHR was significantly improved by the treatment with hesperidin. The contraction responses after l‐NNA were increased in all groups of rats to similar extent, but relaxatory responses were significantly attenuated only in SHR. The inhibition of Kv channels significantly reduced endothelium‐dependent vasodilatory responses in only in SHR administered with hesperidin. The results of our experiment indicate that hesperidin might improve the endothelium‐dependent vasodilation during hypertension, possibly through the enhancement of Kv channels function. Copyright

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).

Trends in vascular pharmacology research in the Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Comenius University, Bratislava

Trends in vascular pharmacology research in the Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Comenius University, Bratislava Research in the Department of Pharmacology started to focus intensively on fetal circulation in the 60s. Results of experiments contributed to clarification of the conversion of fetal circulation type to the adult type: the mechanism of the ductus arteriosus closure, examination of fetal and neonatal pulmonary vessel responses. In the early 80s, increased attention was dedicated to fetal vascular endothelium, later on to vascular reactivity in relation to the endothelium in adult animals. We developed original models of vascular endothelial damage using the perfusion method (repeated vasoconstrictive stimuli, deendothelization by air bubbles). We developed a new technique for in vitro endothelial loss quantification on Millipore filters. Under in vitro conditions, the protective effects of sulodexide and pentoxifylline on vascular endothelium were evaluated. In recent years were studied protective effects of selected substances in vivo in models of endothelial damage (e.g. stress, toxic tissue damage, diabetes mellitus, hypertension). The role of potassium channels in the hypertension model was studied in cooperation with the Czech Academy of Sciences. Assessment of vascular reactivity in the diabetic model was significantly improved by computer. In addition to experimental work, the department is solving problems of clinical pharmacology - especially drug risk evaluation (non-steroidal anti-inflammatory drugs). Recently, we have dealt with pharmacoepidemiological studies in geriatric patients and with cardiovascular risk of NSAIDs in relation to pharmacotherapy. The results of these studies may be an impulse for targeted problem solving in our experiments.

Erratum to “Contribution of Ca2

[This corrects the article DOI: 10.1155/2014/289361.].