Effect of Ramipril, Valsartan, Candesartan and Lacidipine on inflammation and gastric ulcer in rats

The present study investigated and compared the effect of the angiotensin converting enzyme inhibitor ramipril and the angiotensin II receptor blockers valsartan and candesartan and the calcium channel blocker lacidipine on inflammation and gastric ulcer in rats. The acute inflammation was induced by intraplantar injection of carrageenan [1%] in the rat hind paw. Gastric ulcer was evoked by s.c. indomethacin [20 mg/kg]. When given s.c. 30 min prior to induction of inflammation, ramipril [0.23 and 0.45 mg/kg], valsartan [7.5 and 15 mg/kg], candesartan [0.72 and 1.44 gm/kg] failed to reduce paw oedema response. Meanwhile, lacidipine at the lower dose of 0.18 mg/kg displayed mild anti-inflammatory activity up to 1 hr, reducing paw odema by 26.7% for 1 hr post-carrageenan, while a higher dose of 0.36 mg/kg inhibited oedema formation by 33.5, 31, 23.6 and 22.3% at 1, 2, 3 and 4 hr post-carrageenan, respectively. The acute gastric mucosal lesions evoked by indomethacin in the rat were aggravated by co-administration of ramipril 0.23 and 0.45 mg/kg, valsartan 7.5 and 15 mg/kg, lacidipne 0.18 and 0.36 mg/kg and candesartan 0.72 mg/kg, but reduced by candesartan 1.44 mg/kg. Findings in the present study do not favor an anti-inflammatory activity for ramipril, valsartan and candesartan, but indicates an antioedema effect for lacidipine at the doses employed. These agents are likely to adversely affect gastric mucosal integrity and enhance the indomethacin-induced gastric injury

Effects on urinary albumin excretion and renal function changes by delapril and manidipine in normotensive type 2 diabetic patients with microalbuminuria.

This study was designed to investigate the effect of delapril, an ACE inhibitor, and manidipine, a long action calcium antagonist, on persistent microalbuminuria in normotensive type 2 diabetic patients. Sixty type 2 diabetic patients were randomized to take delapril 30 mg/day or manidipine 10 mg/day for 48 weeks, in an open label design. Twenty eight of thirty subjects in the delapril group and twenty nine of thirty in the manidipine group completed the study. Urine albumin excretion as measured by the urinary albumin creatinine ratio decreased significantly in both groups (112.0+/-60.9 to 95.3+/-64.9 mg/g and 108.5+/-51.0 to 96.4+/-53.5 mg/g in the delapril and manidipine group respectively, p < 0.05, by paired t-test). Systolic and diastolic blood pressure were not significantly changed after treatment in the delapril group but significantly decreased in the manidipine group (130.9+/-7.1/80.2+/-6.1 to 127.2+/-7.1/78.0+/-5.3 mm/Hg, p < 0.05, by student's paired t-test). After 48 weeks of treatment, two patients in the delapril group and one patient in the manidipine group converted to normoalbuminuria (urinary albumin:creatinine ratio < 30 mg/g) and one patient in each group progressed to overt nephropathy (urinary albumin:creatinine ratio > 300 mg/g). There were no significant changes in fasting plasma glucose, HbA1c, serum fructosamine, creatinine, potassium and lipid profiles after 48 weeks of treatment in both groups. Two cases in the delapril group were withdrawn during the study because of an intolerable cough and one case in the manidipine group because of intolerable dizziness and headache. In conclusion, both delapril and manidipine are effective in the reduction of microalbuminuria in normotensive type 2 diabetic patients with persistent microalbuminuria.

Synthesis and smooth muscle calcium channel antagonist effect of alkyl. aminoalkyl 1,4 - dihydro - 2,6 - dimethyl - 4 - nitro imidazole - 3,5 pyridine dicarboxylates.

The discovery that 1,4-dihydropyridine [DHP] class of calcium channel antagonist inhibits the Ca+° influx represented a major therapeutic advance in the treatment of cardiovascular diseases such as hypertension, angina pectoris and other spastic smooth muscle disorders. A novel class of calcium channel antagonist of flunarizine containing arylpiperazinyl moiety has recently been reported. It was therefore of interest to determine the effect that selected C-3 substituents contained amino alkyl and arylpiperazine, in conjunction with a C-4 1-methyl-5-nitro-2-imidazolyl substituents on calcium channel antagonist activity. The unsymmetrical analogues were prepared by a procedure reported by Meyer in which 1-methyl-5-nitro-imidazol-2-carboxaldehyde was reacted with acetoacetic esters and alkyl 3-aminocrotonate. In vitro calcium channel antagonist activities were determined by the use of high K+ contraction of guinea pig ileal longitudinal smooth muscle. All compounds exhibited comparable calcium channel antagonist activity [IC50=10[-9] to 10[-11] M] against reference drug nifedipine [IC50=2.75 +/- 0.36 x 10[-10] M]

Conformational flexibility of voltage gated dihydropyridine sensitive calcium channel in hydrated DMPC bilayer.

We have built a model for Ca2+ channel using amino acid sequence from S3 helix of the fourth internal repeat of alpha 1 subunit of dihydropyridine sensitive calcium channel from rabbit skeletal muscle, on the basis of X-ray crystallographic data on four helix bundle. The assembling of the geometry of the pore was achieved using a sixteen residues peptide fragment from short SSI/II loop (residues 1010-1025) which had F1013 and E1014 residues, considered to be important for the drug induced activity of the channel. This had hairpin bend between F1013 to W1016. The drug 2,6-dimethyl 3,5-dicarbomethoxy-4 (2-nitrobenzyl) 1,4 dihydropyridine (DHP) (nifedipine), which is a calcium channel inhibitor used in the treatment of cardiovascular diseases, was introduced, interacting with these two residues via Ca2+ ion. Two more Ca2+ ions were introduced in the pore. The model was incorporated in the bilayer of 36 dimyristoyl phosphatidyl choline (DMPC) molecules with 1201 water molecules and simulated for 200 picoseconds (ps) after equilibration for 120 ps. We also simulated the channel model in vacuum and in aqueous environment for comparison. The latter was unstable after 120 ps. The geometric parameters of the pore are analysed by MOLMOL, PCURVE 3.1 and a special program ANHELIX developed by us. Stability of the pore dimensions during simulations is discussed in this paper.

Calcioantagonistas: acciones e indicaciones / Calcioantagonists: actions and indications

Constituyen un grupo importante de medicamentos ampliamente utilzados en la práctica diaria, que farmacológicamente se caracterizan por bloquear los canales lentos del calcio.

Algunas consideraciones acerca de las drogas bloqueadoras de los canales de calcio / Some considerations about calcium channel blockader drugs

Los bloqueadores de los canales de calcio (dihidropiridinas, verapamilo y diltiazem) son medicamentos de amplio uso en la práctica diaria. Sus principales indicaciones son la hipertensión arterial; la insuficiencia coronaria con angor crónico estable y el síndrome de raynaud. En el último tiempo algunas publicaciones han señalado que el empleo de los calcioantagonistas encerraría el riesgo de aumentar la incidencia de eventos coronarios agudos y de elevar la mortalidad, lo que ha creado inquietud en pacientes y médicos. Aparentemente el riesgo se limita sólo al nifedipino corriente cuando se administra en dosis altas (mayores de 60 mg diarios); indiscriminadamente por vía sublingual (Servicios de urgencia) y a pacientes con infartos miocárdicos agudos o angor inestable. El verapamilo, el diltiazem y los nifedipinos de liberación lenta y acción prolongada no tendrían riesgos

Hibernación miocardica detectada por isradipina en una ventriculografía nuclear / Myocardial hybernation detected by Isradipine in a radionuclide ventriculography

Con el objetivo de detectar viabilidad en la zona de un infarto del miocardio y/o reserva funcional en el tejido residual, se administró 5 mg orales de isradipina, una nueva dihidropiridina antagonista del calcio, a 12 pacientes con antecedentes de un infarto del miocardio. Se realizó una ventriculografía nuclear en reposo antes y 60 minutos después de la isradipina. La fracción de expulsión ventricular izquierda (FEVI) no excedió en ningún caso del 50 por ciento , por lo que un aumento en la motilidad segmentaria afectada fue indicativa de un miocardio en hibernación, mientras que un aumento en la FEVI a expensas de una zona sin afectación segmentaria fue considerado como reserva miocárdica de una segmento isquémico, pero sin necrosis. La media de frecuencia cardíaca, FEVI, y la velocidad máxima de expulsión y llenado aumentaron significativamente con la isradipina, mientras que la presión arterial y el volumen diastólico final disminuyeron. La mitad de los pacientes mejoraron la motilidad segmentaria y la FEVI global

Comparison of the effect of calcium withdrawal from the medium and of blockade of extracellular calcium entry by isradipine on the contractile responses of the isolated rat stomach

The role of calcium in drug-induced contractions of rat gastric fundus strips was evaluated by determining the effect of two procedures on the dose-respponse curves of agonists: a) removal of calcium from the nutrient solution and b) blockade of calcium channels with the dihydrophydine isradipine. Gastric strips were obtanied from adult Wistar rats and suspended in Tyrode solution at 37-C for contraction studies. Dose-response curves for carbachol (CCh), serotonin (5-HT), KCl and BaCl2 were constructed under the two conditions descrived above. A complete blockade of contractile effects was observed for 5-HT and KCl 60 min after calcium withdrawal of after using 3 mM (45 min) of the calcium antagonist. A lower dose of antagonist or a shorter incubation in calcium-free solution caused a partial decrease of dose-response curves, added to a 30-fold shift to the right after the calcium antagonist (1mM), or a larger than 100-fold shift 3 min after calcium removal. In contrast, dose-response curves for CCh and BaCl2 were not significantly affected by either type of treatment. It is concluded that 5-HT and KCl utilize extracellular sources of calcium, whereas CCh or BaCl2 depends on a tightly-bound calcium pool in this preparation

Enterolobin induces rat paw oedema independently of PAF-acether

The potential participation of PAF-acether (PAF) on the paw oedema triggered by enterolobin was investigated. Intraplantar injections of enterolobin )5-20 µg/paw) yielded a dose response curve for edema which appeared after 30 min, peaked in the interval between 2-4 h and faded after 24h. The pre-treatment with BN 52021, but not with other PAF antagonists such as PCA 4248 or WEB 2086, significantly blocked enterolobin-induced oedema. To clarify better the discrepant results obtained with the PAF antagonists, desensitization to PAF was performed. The oedema triggered by enterolobin was not modified in paf desensitized animals. It was concluded that the paw inflammation induced by enterolobin does not require PAF mechanism.