枸橼酸西地那非,动物实验 z-bo 2020-09-07 425

　　Background: Sildenafil Citrate is the first phosphodiesterase type 5 (PDE-5) inhibitor to be approved for the treatment of erectile dysfunction and has become one of the most widely prescribed drugs in the world. The drug inhibits PDE5, the enzyme that hydrolyzes cyclic guanosine phosphate (cGMP), and regulates the circulating level of cGMP, which in turn leads to relaxation of the corpus cavernosum and increased local blood flow. However, PDE5 is not only present in the corpus cavernosum, but also in peripheral arterial and venous smooth muscle cells, as well as in the lung and coronary circulation, platelets and vascular endothelial cells. Therefore, PDE5 inhibitor drugs can cause systemic hemodynamic changes. Although the drug is widely used to treat erectile dysfunction, some users exhibit visual side effects such as blurred vision and increased sensitivity to light. These symptoms are related to the cross-inhibition of phosphodiesterase type 6 drugs present in the retina, and are involved in the regulation of the light transmission mechanism. However, there is no consensus on the role of sildenafil citrate in inhibiting the retina and retrobulbar blood flow in inhibiting PDE5 in the blood vessel wall of these areas. Identifying and quantifying the vasodilator activity in the retrobulbar circulation caused by sildenafil citrate can provide important clinical information, especially for patients with ocular reflex vasoconstriction conditions, such as retinal hypertension in patients with renal failure. Chronic hypertension causes continuous compensatory vasoconstriction of retinal arterioles, causing ischemia and retinal degeneration, impairing the function of this tissue. Considering the potential of sildenafil citrate to treat eye diseases with reflex vasoconstriction, the purpose of this study is to determine whether the drug has blood vessels based on the evaluation of ocular perfusion pressure and color Doppler imaging of the external ophthalmic artery The effect of dilators on the retro-eye circulation of healthy rabbits.

　　Methods: Animals and experimental design: In this study, 14 healthy adult male New Zealand white rabbits with an average weight of 2.5 kg. The sample size is based on the number required to obtain reliable statistical results. After a clinical examination by the veterinarian, the eyes and general health of the animal were considered normal. The rabbits are raised in a single cage, free to eat and drink, and the temperature is 24±1°C. The rabbits were divided into two groups, seven in each group (n=7), the control group (C) and the treatment group (S). Group (C) took 1.5 ml of saline, and the control group took 10 mg of sildenafil citrate. Both groups were treated at 24 hour intervals for continuous treatment for 30 days. Experimental protocol: (1) oral sildenafil vasodilator, (2) measurement of intraocular pressure (IOP), (3) measurement of mean arterial pressure (MAP), and color Doppler ultrasound imaging of the external ocular artery. For oral sildenafil citrate, allow 45 to 60 minutes of waiting time between the ingestion of the drug and the subsequent steps. Assessments are conducted once a week: Day 1 (M1), Day 7 (M2), Day 14 (M3), Day 21 (M4), and Day 30 (M5). To measure IOP and MAP and Doppler studies, unsedated rabbits were wrapped in towels, leaving only the head for the researchers to measure. During the evaluation, no excessive force was used to restrain the animal. In order to reduce the restraint period, only the right eye of each animal was checked, so as to avoid the influence of stress on the retrobulbar circulation and optimize the action time of the drug.

　　Intraocular pressure measurement: Use Too-PoN AVAS VET? Applanation tonometer to measure rabbit intraocular pressure. The procedure involves gently lifting the eyelids, dripping 0.5% proparacaine on the eyes, and measuring with a tonometer five minutes later.

　　MAP measurement: After incising and preserving the dorsal surface of rabbit ears, the central artery was intubated with a 24G catheter. Then insert the catheter into the semi-rigid silicone tube system. In this system, two silicone tubes are connected to a three-way stopcock. The free end of one tube is fixed with a catheter, and the other end is a BD sphygmomanometer. The system was then filled with 1 ml heparin/1000 ml 0.9% saline. The air/liquid interface is located at the height of the right atrium and the eye, and the mean arterial pressure is read with a sphygmomanometer.

　　OPP calculation: The intraocular perfusion pressure (OPP) is determined by subtracting the mean arterial pressure (MAP) from the intraocular pressure (IOP), as described by Kiel & Huvin.

　　Color Doppler imaging: Use Mylab’s 30 veterinary ultrasound system coupled to a 13-18 MHz linear transducer for color Doppler evaluation of the external ophthalmic artery. Before the examination, the cornea was anesthetized by a drip of 0.5% proparacaine hydrochloride local anesthetic. Then apply a sterile water-based gel layer to the surface of the cornea, and gently place the sensor in the longitudinal position with the position indicator facing the upper eyelid. Record the sagittal image of the eyeball and optic nerve in a two-dimensional mode. Color Doppler ultrasound was used to observe the position of the external ocular artery near the entrance of the optic nerve. Then the pulse wave Doppler cursor was immediately positioned on the ophthalmic artery, and the blood flow curve in the vascular cavity was recorded by a uniform acoustic emission method. On this basis, the curve was used to evaluate the peak systolic velocity (PSV) and end-diastolic velocity ( EDV). The angle is not corrected, and the measurement is not greater than 60°. According to the PuleloT equation (Ri=PSVαEVS/PSV), Mylab software is used to automatically calculate the ocular arterial resistance index (RI), and the curve is analyzed with the same operator (APAC), and the PSV and EDV of the three continuous curves are marked .

　　Statistical method: A randomized 2×5 split area trial design was used, with corresponding treatments (with and without sildenafil citrate), to evaluate M1-M2-M3-M4-M5, from each animal to one experiment group. Using R? statistical software, the data was tested for normality by Shapiro-Wielk test, and analysis of variance was performed. Use the TUKEY test method for comparison.

　　Results: intraocular perfusion pressure: the average baseline IOP, MAP and OPP values of the two groups were 11.85 mmHg, 80.71 mmHg and 68.85 mmHg, respectively. Under the experimental conditions, the MAP and OPP values of the group (S) were higher than those of the control group (C) in M1 (S=71.52 mmHg, C=84.76 mmHg, P=0.0356) and M5 (S=71.38 mmHg) , C=85.52 mmHg, P=0.0252), there is a statistical difference. However, there was no statistical difference in IOP values during the experiment.

　　Color Doppler imaging: Before treatment, the average baseline value of the right eye artery of the two groups of rabbits was 22.99 cm/s, the EDV was 12.29 cm/s, and the resistance index was 0.53. The extraocular arteries show red blood flow in color Doppler, showing a laminar flow pattern with moderate resistivity, dichroism and two peak systolic velocities. However, under the experimental conditions, the color Doppler ultrasound values of the test groups were not statistically different.

　　Discussion: This study found that sildenafil citrate reduced the mean arterial pressure of rabbits. In humans, this drug has also been found to cause a significant decrease in systolic and diastolic blood pressure one hour after ingestion. However, other studies have found that there is no change in blood pressure after taking the drug. Although MAP was significantly reduced at M1 and M5, the treated animals did not have hypotension because the normal blood pressure of this species ranges from 70 mm Hg to 170 mm Hg.

　　Conclusion: According to the data obtained in this study, it can be pointed out that sildenafil at a dose of 10 mg causes systemic vasodilation in healthy rabbits and reduces their average arterial pressure and intraocular perfusion pressure. However, the drug does not cause changes in the hemodynamics of the extraocular arteries, nor does it change intraocular pressure.