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CORRECTION OF RETINAL ANGIOPATHY OF HYPERTENSIVE TYPE BY MINOXIDIL, SILDENAFIL IN EXPERIMENT

For the study of retinoprotective properties of pharmacological agents a model of retinal angiopathy of hypertensive type was created against the background of N-nitro-L-arginine methyl ester (L-NAME) administration in a dose 12.5 mg/kg rat body weight for 28 days. We studied the retinoprotective effects of minoxidil in a dose 0.5 mg/kg, sildenafil in a dose 0.5 mg/kg and distant ischemic preconditioning (DIP) on a model of retinal angiopathy of hypertensive type in Wistar rats. The experiment showed that minoxidil in a dose 0.5 mg/kg prevented the development of ischemic damage and retinal vascular changes of hypertensive type caused by the introduction of L-NAME for 28 days, to a greater extent than sildenafil and distant ischemic preconditioning. The observed retinoprotective effects are confirmed by ophthalmoscopy, laser Doppler flowmetry (LDF) and electroretinography (ERG). The lack of positive dynamics in experimental groups with the introduction of glibenclamide in a dose 5 mg/kg confirms the key role of ATP-dependent potassium channels in the mechanism of realization of preconditioning. Detection of preconditioning properties of pharmacological agents may be a new approach in the correction and prevention of retinal angiopathy, which is the initial part of hypertensive retinopathy.

Иллюстрации

Table 1. Methods of integrated semiquantitative evaluation of the fundus changes, detected during ophthalmoscopy (in grades).

Figure 1. Example of ophthalmoscopy on intact Wistar rat. Optic disc is circular or oval shape and stands out from the fundus in pale - pink. The boundaries of the optic nerve disc are clear. It lies in the plane of the retina. From the middle of the optic nerve exit the central vessels of the retina. Blood vessels of the retina don`t have anastomoses. The veins and arteries are straightforward, caliber is uniform, not crimped. The general background is pink.

Figure 2. Example of ophthalmoscopy on Wistar rat with retinal angiopathy of hypertensive type. Optic disc is circular or oval shape and stands out from the fundus in pink. The boundaries of the optic nerve disc are clear. Veins are congested, full-blooded, crimped at the periphery. Arteries are narrowed, slightly crimped. Retina is palely (ischemic). No hemorrhage. Symptom Salus-Hun I-III (arrows show).

Table 2. Integral assessment of fundus changes, detected during ophthalmoscopy (scores 0-5; n = 10).

 

Figure 3. Example of ophthalmoscopy on Wistar rat with the correction of retinal angiopathy of hypertensive type by minoxidil in a dose of 0.5 mg/kg on day 29 of the experiment. Optic disc is circular or oval shape and stands out from the fundus in pale - pink. The boundaries of the optic nerve disc are clear. It lies in the plane of the retina. Blood vessels of the retina don`t have anastomoses.  The veins and arteries are straightforward, no crimping. Slightly dilated veins at the periphery. The general background is pink, not ischemic.

Figure 4. Example of ophthalmoscopy on Wistar rat with the correction of retinal angiopathy of hypertensive type by sildenafil in a sode 0.5 mg/kg on day 29 of the experiment. Optic disc is circular or oval in shape and stands out from the fundus in pale - pink. The boundaries of the optic nerve disc are clear. It lies in the plane of the retina. There is a slight vasoconstriction, "the phenomenon of chiasm", a symptom Salus-Hun I (arrow). Veins are crimped at the periphery. The background is slightly paly.

Figure 5. Example of ophthalmoscopy on Wistar rat with the correction of retinal angiopathy of hypertensive type by distant ischemic preconditioning on the 29 day of the experiment. Optic disc is circular or oval shape and stands out from the fundus of the eye in pink. The boundaries of the optic nerve disc are clear. It lies in the plane of the retina. There is a slight vasoconstriction, "the phenomenon of chiasm", a symptom Salus-Hun I, II (arrows show). Expansion of veins on both sides of the chiasm. Veins are crimped at the periphery. The background is slightly paly.

Table 3. Influence of minoxidil, sildenafil and DIP on the complex fundus changes, found during ophthalmoscopy, on model of retinal angiopathy of hypertensive type (n = 10).

Table 4. Level of microcirculation in rat retina on day 29 of the experiment (M ± m; n = 10), p.u.

Table 5. The results of evaluation of retinal electrophysiological state on day 29 of the experiment (M ± m; n = 10) r.u.

Figure 6. Electroretinogram of rats: A – ERG of intact animal; B – ERG of animal with retinal angiopathy of hypertensive type (inhibition of b-wave is observed) on day 29 of the experiment.

DOI: 10.18413/2500-235X-2016-2-4-34-44
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