Variations in Chemical Composition, Vasorelaxant and Angiotensin I-Converting Enzyme Inhibitory Activities of Essential Oil from Aerial Parts of Seseli pallasii Besser (Apiaceae).

The present paper describes environmental and seasonal-related chemical composition variations, vasorelaxant and angiotensin I-converting enzyme (ACE) activities of essential oil from aerial parts of Seseli pallasii Besser. The composition was analyzed by GC and GC/MS. Monoterpenes were found to be the most abundant chemical class with α-pinene (42.7 - 48.2%) as the most prevalent component. Seseli pallasi essential oil relaxed isolated endothelium-intact mesenteric arteries rings precontracted with phenylephrine with IC50  = 3.10 nl/ml (IC50  = 2.70 µg/ml). Also, S. pallasii essential oil was found to exhibit a dose-dependent ACE inhibitory activity with an IC50 value of 0.33 mg/ml. In silico evaluation of ACE inhibitory activity of the individual components showed that spathulenol exhibited the best binding affinity with ACE, and the lowest binding energy of -7.5 kcal/mol. The results suggested that combination of vasorelaxing and ACE inhibitory effects of the analyzed S. pallasii essential oil might have the potential therapeutic significance in hypertension.

Effects of protamine sulphate on spontaneous and calcium-induced contractile activity in the rat uterus are potassium channels-mediated.

Protamine sulphate (PS) effect on spontaneous and calcium-induced rhythmic contractions of isolated virgin rat uteri was studied. PS caused dose-dependent relaxation of both types of contractions (two-way ANOVA, significant dose effects). Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME; 10(-5) mol/l), methylene blue (MB; 0.9 x 10(-6) mol/l) or propranolol (1.7 x 10(-5) mol/l) enhanced PS-mediated uterine muscle relaxation of spontaneous contractions. Dosedependent relaxation of spontaneous active isolated rat uterus with PS was lower in uteri pretreated with single dose of tetraethylammonium (TEA; 6 x 10(-3) mol/l), glibenclamide (2 x 10(-6) mol/l) and 4-aminopyridine (4-AP; 10(-3) mol/l). Calcium-induced activity of the isolated rat uterus pretreated with the same concentration of L-NAME, MB, or propranolol modified the kinetic of PS-induced relaxation without changes in EC(50) values. Pre-treatment with glibenclamide, TEA and 4-AP significantly reduce PS relaxing effect of calcium-induced activity and according to EC(50) values the order of magnitude was glibenclamide > TEA > 4-AP. PS is mixture of polyamines and may activate different signal-transduction pathways. Our results cleary demonstrate that in uterine smooth muscle PS act dominantly through potassium chanels and marginaly through beta-adrenergic receptos or nitric oxide-dependent pathways.

The antinociceptive effects of anticonvulsants in a mouse visceral pain model.

BACKGROUND: There is evidence supporting the antinociceptive effects of carbamazepine, oxcarbazepine, gabapentin, and topiramate in various models of neuropathic pain as well as inflammatory somatic pain. Data are lacking on the antinociceptive potential of these drugs against visceral pain. In this study, we examined and compared the effects of carbamazepine, oxcarbazepine, gabapentin, and topiramate in the writhing test as a visceral pain model in the mouse. In addition, the influence of these anticonvulsants on motor performance was examined to compare the tolerability of these anticonvulsants when used against acute visceral pain. METHODS: The antinociceptive effects of these anticonvulsants were examined in the acetic acid writhing test in mice. The side effect propensity of these drugs was examined using the rotarod test. RESULTS: Carbamazepine (25-60 mg/kg; p.o.), oxcarbazepine (10-40 mg/kg; p.o.), gabapentin (10-70 mg/kg; p.o.), and topiramate (5-30 mg/kg; p.o.) caused a significant dose-dependent reduction the number of writhes in the writhing test. In the rotarod test, carbamazepine (60-140 mg/kg; p.o.) and oxcarbazepine (120-450 mg/kg; p.o.) significantly reduced the time spent on the rotarod in a dose- and time-dependent manner. Gabapentin (1000-2000 mg/kg; p.o.) and topiramate (400-1500 mg/kg; p.o.) did not produce significant impairment of motor performance at the highest doses used. The therapeutic index (motor impairing dose TD(50)/writhing ED(50)) values were topiramate (>148.5) > gabapentin (>60.2) > oxcarbazepine (15.2) > carbamazepine (2.3). CONCLUSIONS: These results indicate that oxcarbazepine, gabapentin, and topiramate are effective in the writhing model in mice, in a dose range, which is not related to motor impairment; topiramate is the most potent and the most tolerable drug.

The effect of potassium channel opener pinacidil on the non-pregnant rat uterus.

The effects of the K(+) channel opener, pinacidil on the spontaneous rhythmic contractions and contractions provoked by electrical field stimulation (50 Hz) or by oxytocin were investigated in the isolated uterus of the non-pregnant rat in oestrus. Pinacidil produced more potent inhibition of oxytocin-elicited contractions than of spontaneous rhythmic contractions or electrical field stimulation-induced contractions. Glibenclamide, a selective blocker of adenosine triphosphate (ATP)-sensitive K(+) (K(ATP)) channels, antagonized the pinacidil-induced inhibition of contractions elicited by oxytocin in a competitive manner. However, the pinacidil-induced inhibition of electrical field stimulation-elicited contractions and spontaneous rhythmic contractions was antagonized non-competitively by glibenclamide. In the uterine strips pre-contracted with 80 mM K(+), the pinacidil-induced maximal relaxation was not affected. The present data show that pinacidil exhibits potent relaxant properties in the rat non-pregnant uterus in oestrus and therefore should be taken into account as a possible agent for treatment of dysmenorrhoea. Based on glibenclamide affinity, it appears that the inhibitory response to pinacidil involves K(ATP )channels. We need further investigations to explain why the interaction between glibenclamide and pinacidil in this experimental model depends on the nature of contractions. The ability of pinacidil to completely relax the rat non-pregnant uterus pre-contracted with K(+)-rich solution suggests that K(+) channel-independent mechanism(s) also play a part in its relaxant effect.

Different responses of mesenteric artery from normotensive and spontaneously hypertensive rats to nitric oxide and its redox congeners.

The conversion of nitric oxide (NO*) into its congeners nitrosonium (NO(+)) and nitroxyl (HNO/NO(-)) ions may have important consequences for signal transduction and physiological responses. Manganese-containing superoxide dismutase (MnSOD) may convert NO. into its redox congeners. In our current work, we have examined the mechanism of sodium nitroprusside (SNP)-induced relaxation of arteries, with or without endothelium, from both normotensive and spontaneously hypertensive (SH) rats in the absence and presence of MnSOD. SNP induced a greater degree of relaxation in normotensive than in SH rats. MnSOD antagonized SNP-induced relaxation and effect was greater in normotensive than hypertensive rats. However, MnSOD even potentiated SNP-induced relaxation in mesenteric arteries with endothelium from SH rats. Our results indicate that HNO/NO(-)-mediated relaxation is more effective in mesenteric artery smooth muscle from SH rats than from normotensive rats and that vascular dysfunction in SH rats is not solely endothelium-derived but involves changes in vascular smooth muscles.

Reversible oxidation of myometrial voltage-gated potassium channels with hydrogen peroxide.

The uteri, spontaneously active or Ca(2+) (6 mM) induced, were allowed to equilibrate, and to inhibit voltage-gated potassium (K(V)) channels 1 mM 4-amino pyridine (4-AP) was applied for 15 min before adding H(2)O(2). H(2)O(2) was added cumulatively: 2 µM, 20 µM, 200 µM, 400 µM, and 3 mM. Average time for H(2)O(2) concentrations (2, 20, 200, and 400) µM to reach its full effect was 15 min. H(2)O(2) 3 mM had a prolonged effect and therefore was left to act for 30 min. Two-way ANOVA showed significant differences in time dependency between spontaneous and Ca(2+)-induced rat uteri after applying 3 mM H(2)O(2) (type of contraction, P = 0.0280), but not 400 µM H(2)O(2) (P = 0.9271). Our results indicate that H(2)O(2) oxidises channel intracellular thiol groups and activates the channel, inducing relaxation. Cell antioxidative defence system quickly activates glutathione peroxidase (GSHPx) defence mechanism but not catalase (CAT) defence mechanism. Intracellular redox mechanisms repair the oxidised sites and again establish deactivation of K(V) channels, recuperating contractility. In conclusion, our results demonstrate that K(V) channels can be altered in a time-dependent manner by reversible redox-dependent intracellular alterations.

Effect of indometacin pretreatment on protamine sulfate-mediated relaxation of the isolated rat uterus: the role of the antioxidative defense system.

Previous results in this laboratory indicate that protamine sulfate (PS) evokes dose-dependent relaxation of both spontaneous and calcium ion-induced uterus activity mediated predominantly by potassium channels and, to a small extent, via ß-adrenergic receptors or nitric oxide (NO)-dependent pathways. Indometacin is a nonselective inhibitor of cyclooxygenase (COX 1 and COX 2) that has the ability to delay premature labor by reducing uterine contractions through the inhibition of prostanglandin synthesis in the uterus. This study investigates the effects of indometacin (0.1 and 1 µg/ml) pretreatment on the PS-induced relaxation of isolated uterine smooth muscle. Indometacin pretreatment per se did not change the activity of the uteri. However, indometacin significantly increased PS-induced relaxation of spontaneous uterine contractions. Indometacin pretreatment significantly decreased the magnitude and slope of PS-induced relaxation of calcium ion-induced uterine contractions. Indometacin pretreatment increased CuZnSOD activity and slightly increased GR activity during spontaneous uterine contractions when compared to PS alone. In calcium ion-induced contractions, indometacin pretreatment increased CuZnSOD, GSH-Px and GR activities. These results suggest that, in addition to its COX inhibitory effects, indometacin influences the effects of PS. Therefore, it is possible that indometacin regulates diverse cell functions via its association with lipid membranes by altering micro-environments within the membranes. The above-mentioned processes appear to be partly mediated by redox processes involving ROS, lipid peroxides and antioxidant enzymes. The extent of the PS-mediated effect as different in spontaneous versus calcium ion-induced active uteri.

Diethyldithiocarbamate potentiates the effects of protamine sulphate in the isolated rat uterus.

Protamine sulphate causes potassium ion channel-mediated relaxation of spontaneous and calcium ion-induced contractions of the isolated rat uterus. Diethyldithiocarbamate (DDC) potentiated the effect of protamine sulphate. A mechanism for DDC's action was postulated on the basis of its interactions with divalent iron ions and Cu,Zn-SOD. DDC chelates divalent iron ions creating DDC-iron (Fe-DDC) complexes. Fe-DDC forms stable NO-Fe-DDC(2) complexes by NO scavenging and de-nitrosylation processes, which in combination with DDC (5 mM) provoke inhibition of Cu,Zn-SOD resulting in specific oxidative conditions culminating in potassium ion channel opening, membrane hyperpolarisation, inhibition of calcium ion influx and subsequent muscle relaxation. As Fe-DDC and NO-Fe-DDC(2) complexes exclude divalent iron ions from participating in the hydroxyl radical generating Fenton reaction, DDC can also prevent iron-related pathophysiological manifestations. Such permissive roles of DDC open the possibility for application of its pharmacological form (disulfiram) to a wider spectrum of pathophysiological conditions related to smooth muscles.

[Relaxant effects of protamine sulfate on isolated renal arteries of normotensive and hypertensive rats]. / Relaksantni efekat protamin-sulfata na izolovanim renalnim arterijama normaotenzivnih i hipertenzivnih pacova.

INTRODUCTION: Protamine sulfate is found to have endothelium-dependent relaxing effect on isolated blood vessels. The aim of our experiments was to study relaxant effects of protamine sulfate on isolated renal arteries of both normotensive and hypertensive rats. MATERIAL AND METHODS: Experiments were performed on renal arteries, isolated from male, Wistar, spontaneously hypertensive rats (250-300 g). The adhering perivascular tissue was carefully removed from arteries which were then cut into 3-5 mm ring segments, incubated 30 min in water bath in Krebs-Ringer bicarbonate solution at 36 degrees C, and gassed with 95% O2 and 5% CO2. Each was gradually stretched to optimal tension (2 g) and isometric transducer registered mechanical contractions. Contractions of isolated blood vessels were caused by phenylephrine (10(-6) mol) and functional integrity of the endothelium was confirmed by acetylcholine (10(-5) mol) and histopathological examination. RESULTS AND DISCUSSION: Preparations were analyzed using a microscope to distinguish differences between blood vessels of normotensive and hypertensive rats. The reason for this effect of protamine is probably its stimulating effect on nitrogen-monoxide release, which might be the main reason for systemic hypotension that occurs during protamine infusion. It occurs due to activation of endothelial NO-synthesis. Our results show a better relaxant effect of protamine with normotensive, comparing to hypertensive rats, regarding to better preservation of endothelium with normotensive animals. CONCLUSION: The relaxant effect of protamine occurs due to NO release with conductance artery, which is not the case with microvessels, where this effect occurs due to endothelium-derived hyperpolarizing factor release.

Comparison of the relaxant effects of a new oxime-nitrate derived from isosorbide-5-mononitrate and the parent drug.

The transformation of isosorbide-5-mononitrate (CAS 16051-77-7, IS-5-MN) to the corresponding keto derivative and its ketoxime (oxime-nitrate derivative of isosorbide) is described. The effects of IS-5-MN and the new oxime-nitrate (ON) on the endothelial and smooth muscle cells of isolated rings of the rat superior mesenteric artery were examined. After contraction induced by phenylephrine, IS-5-MN (10(-8)-10(-4) mol/l) caused a concentration-dependent relaxation. Removal of the vascular endothelium strongly potentiated this effect. On the other hand, the new ON (10(-8)-10(-4) mol/l) was a more potent relaxant than the parent drug, but its effect was not dependent on the vascular endothelium. The inhibitory effect of the artery without endothelium to the new ON was more pronounced than that to IS-5-MN. The mechanism of the relaxant effect of the new compound consisted in the liberation of nitric-oxide (NO) which activated guanylate cyclase (GC), upon which accumulation of cyclic guanosine monophosphate (cGMP) occurred, which was the second messenger leading to relaxation. Tolerance to the frequent applications of the new compound was not observed, moreover a slight increase of the effect was detected in comparison with IS-5-MN for which tolerance was observed to a great extent. Clinically, the new ON could be favorable in all types of angina in comparison with the classical IS-5-MN.