Медицина/6. Экспериментальная и клиническая фармакология

MD Pokrovskaya T.G.¹, Dudina E.N.², Konovalova E.A.², Full Prof. Pokrovsky M.V.¹, MD Kochkarov V.I.¹, PhD Kolesnik I.M.², MD Korokin M.V.¹, Filimonov V.M.², Dolzhikova I.N.¹

¹Federal State Autonomous Institution of Higher Professional Education "Belgorod State National Research University", Russia

²State Educational Institution of Higher Professional Education "Kursk State Medical University", Ministry of Health, Russia

Correction of endothelial dysfunction by inhibitors of phosphodiesterase-5 in combination with L-arginine

The last decade was marked by intense study of inhibitors of phosphodiesterase-5 (IFDE-5), which was originally used as a medicine for the treatment of erectile dysfunction, in pulmonology, cardiology, gastroenterology, gynecology and related specialties [2]. In addition, at the present time much attention is paid to the role and place of L-arginine, a precursor of nitric oxide (NO), in correction of endothelial dysfunction.

The purpose of this study is a comparative evaluation of dose-response endothelioprotective effects of small doses of sildenafil and tadalafil in combination with L-arginine in experimental modeling violations pathway L-arginin/NO caused exogenous blockade of endothelial NO-synthase.

The experiments were performed on white male Wistar rats weighing 250-300 g. Nonselective NO-synthase blocker, N-nitro-L-arginine methyl ester (L-NAME) was administered intraperitoneally at a dose of 25 mg/kg/day. On day 8 of the experiment, under anesthesia (chloral hydrate 250 mg/kg) was administered to the catheter in the left carotid artery for recording of blood pressure (BP) during vascular tests, bolus administration of pharmacological agents to the right femoral vein. Hemodynamic parameters: systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) were measured continuously by means of sensor P23ID «Gould» USA and computer program «Bioshell». Conducted following functional vascular test: endothelium dependent vasodilatation (EZV) - intravenous injection of acetylcholine (ACh) in a dose of 40 mg/kg, endothelium independent vasodilatation (ENZV) - intravenous administration of sodium nitroprusside (NP) in a dose of 30 mg/kg [1]. The test group of animals (n = 10): I - intact; II - with the introduction of L-NAME; III - with the introduction on the background of L-NAME sildenafil (Viagra, «Pfizer») -0,22 mg/kg intraperitoneally, two-night ; IV - with the introduction on the background of L-NAME tadalafil (Cialis, «Lilly / ICOS») -0,09 mg/kg intraperitoneally, once a day, V - with the introduction on the background of L-NAME sildenafil - 0.22 mg/kg intragastrically, double a day and L-arginine (EUROBIOPHARM GmgH, Hamburg) - 200 mg/kg, ip, once a day; VI - with the introduction on the background of L-NAME tadalafil-0, 09 mg / kg intraperitoneally, once a day and L-arginine, 200 mg/kg, ip, once a day.

Intravenous bolus ACh for 3-5 seconds led to a sharp drop in blood pressure to peak in intact animals for systolic blood pressure (SBP) 84,3 ± 4,4, for diastolic blood pressure (DBP) - 38,7 ± 2,8 and for mean arterial pressure (Circadian BP rhythm) 53,9 ± 2,7 mm Hg. Art., while in the first 2-3 seconds developed severe bradycardia to 130-150 beats per minute. Restoration of blood pressure occurred in average 42,2 ± 0,8 sec. after normalizing heart rhythm. ENZV also characterized by lower SBP to 83,0 ± 3,7, DBP to 42,1 ± 4,4 and Circadian BP rhythm to 55,7 ± 3,5 mmHg followed by complete recovery in an average of 45,1 ± 1,0 sec. The blockade of NO-synthase with a long, every day, for 7 days intraperitoneal L-NAME (N-nitro-L-arginine methyl ester, 25 mg/kg) induced hypertension (SBP - 190,3 ± 6,7 , DBP - 145,0 ± 3,9, Circadian BP rhythm - 160,1 ± 4,6 mm Hg. cent.) and led to a smaller reduction of blood pressure after administration of ACh (SBP to 110,6 ± 5,2, DBP to 82 , 8 ± 6,6, Circadian BP rhythm to 92,1 ± 6,1 mm Hg. cent.) and NP (SBP to 88,7 ± 4,7, DBP to 50,8 ± 4,2 to 63,4 and Circadian BP rhythm ± 4,1 mm Hg. cent.) compared to intact animals.

In assessing hemodynamic between groups noted the following dynamics of numbers of blood pressure: the greatest part hypotensive effect seen with the introduction of a low dose of sildenafil in combination with L-arginine. Thus, the parameters of BP zageristrirovannye sildenafil monotherapy were-SAD - 199,8 ± 3,8 mm Hg. Art. and DBP - 166,1 ± 2,5 mm Hg. Art., and in combination with L-arginine and 169,9 ± 10,0 135,7 ± 7,7 mm Hg. Art. respectively. With the introduction of low-dose tadalafil significant hypotensive effect was not observed, BP readings were SBP - 189,9 ± 8,5 and DBP-153,3 ± 6,4 mm Hg. Art. and its combination with L-arginine monotherapy and tadalafil, respectively. In combination tadalafil low dose of L-arginine as hypotensive effect was not observed.

During the functional tests to assess cardiovascular pharmacological correction of L-NAME-induced deficiency of nitric oxide, we used the ratio of endothelial dysfunction (CED), proposed in our laboratory, which reflects the ratio of calculated indicators and ENZV EZV. In the group with the introduction of L-NAME CED was 5,4 ± 0,6 standard units, and in the group of intact animals - 1,1 ± 0,1 conv. ed, therefore, the closer the obtained values of CED in the experimental groups, the higher the degree of correction of the simulated ED.

After the calculation of the ratio of the area of the reaction curve during ENZV EZV and in all experimental groups of manifestations of pharmacological correction of endothelial dysfunction. In the expression of endothelioprotective modeling effects with L-NAME-induced deficiency of nitric oxide, study drugs can be arranged in series in the degree of increase as follows: sildenafil (0.22 mg/kg) - (CED = 3,2 ± 0,2 conv . pcs.) → tadalafil (0.09 mg/kg) - (CED = 2,9 ± 0,1 conv) → sildenafil (0.22 mg / kg) + L-arginine (200 mg/kg) - (2,5 ± 0,2 conv. U ..) → tadalafil (0.09 mg / kg) + L-arginine (200 mg/kg) - 2,1 ± 0,2 conv.

So, the results allow to ascertain effective correction of endothelial dysfunction with sildenafil and tadalafil on L-NAME-induced deficiency of nitric oxide and in small doses (reduced compared to the average of 10 therapeutic). In addition, the combined use of sildenafil and tadalafil in small doses with L-arginine showed an additive endothelioprotective effect.

The study was supported by a grant of the President of the Russian Federation № MK-905.2012.4.

The study was conducted as part of the state task for R & D (State Contract № 4.913.2011).

References:

1. Pokrovskaya TG, Kochkarov VI, Basil M. etc. The principles of pharmacological correction of endothelial dysfunction / / Cuban Research Medical Journal. - 2007. - № 1-2. - P. 146-149.

2. Pokrovskaya TG, Chulyukova TN, Basil M. Endothelioprotective effects of sildenafil and tadalafil experimental modeling of L-name-induced deficiency of nitric oxide / / Cuban Research Medical Journal. - 2009. - № 4. - P. 136-145.