Colahan P T, Jackson C A, Rice B, Szabo N, Jones J H
Equine Performance Laboratory, College of Veterinary Medicine, University of Florida, Gainesville, USA.
Equine Vet J Suppl. 2010 Nov(38):606-12. doi: 10.1111/j.2042-3306.2010.00286.x.
Sildenafil, a phosphodiesterase-5 inhibitor vasodilator, increases cGMP concentrations by inhibiting enzymatic degradation. Marketed to treat erectile dysfunction in men, it also reduces pulmonary arterial pressure (PAP). Because it reduces PAP, sildenafil may enhance performance and/or prevent exercise induced-pulmonary haemorrhage (EIPH).
To determine if sildenafil citrate administration altered commonly measured indices of performance or reduced EIPH in exercised horses.
Thirteen athletically conditioned Thoroughbred horses (2 mares and 11 geldings, age 3-12 years) were administered sildenafil citrate or placebo in 2 crossover design exercise testing studies. In a step-wise test to exhaustion, inspired/expired gas analysis, blood lactate, heart rate, runtime and bronchoalveolar lavage (BAL) cytology were measured. In a 13 m/s test to exhaustion, blood lactate, heart rate, runtime, BAL cytology and pulmonary arterial pressure were measured. Data were analysed with paired and unpaired t tests, one-way ANOVA and Tukey's pair-wise multiple comparison and Friedman repeated measure analysis of variance on ranks.
The administration of sildenafil did not alter mean inspired/expired gas measurements, plasma lactate concentrations or acute pulmonary haemorrhage in either exercise test or pulmonary arterial pressure measurement in the 13 m/s trial. Heart rates in both stress tests were significantly different at submaximal speeds and during the early recovery period. Run time was not affected by sildenafil administration in the step-wise trial (P = 0.622) or in the 13 m/s trial (P = 0.059).
Sildenafil did not alleviate pulmonary haemorrhage or enhance performance-related indices in these trials. Sildenafil administration altered cardiovascular adaptation to intense exercise as evidenced by altered heart rates at submaximal speeds and post exercise. The effect of these alterations on other performance perimeters was not evident.
西地那非是一种磷酸二酯酶-5抑制剂血管扩张剂，通过抑制酶降解来提高环磷酸鸟苷（cGMP）浓度。它在市场上用于治疗男性勃起功能障碍，同时也能降低肺动脉压（PAP）。由于西地那非可降低肺动脉压，它可能会提高运动表现和/或预防运动诱发的肺出血（EIPH）。
确定给予柠檬酸西地那非是否会改变运动马匹常用的运动表现指标或减少运动诱发的肺出血。
在两项交叉设计的运动测试研究中，对13匹经过运动训练的纯种马（2匹母马和11匹阉马，年龄3至12岁）给予柠檬酸西地那非或安慰剂。在逐步递增至力竭的测试中，测量吸入/呼出气体分析、血乳酸、心率、运动时间和支气管肺泡灌洗（BAL）细胞学指标。在以13米/秒速度递增至力竭的测试中，测量血乳酸、心率、运动时间、BAL细胞学指标和肺动脉压。数据采用配对和非配对t检验、单因素方差分析、Tukey成对多重比较以及Friedman秩次重复测量方差分析进行分析。
在任何一项运动测试中，给予西地那非均未改变平均吸入/呼出气体测量值、血浆乳酸浓度或急性肺出血情况，在13米/秒速度测试中的肺动脉压测量值也未改变。在两个应激测试中，亚最大速度和恢复早期的心率均有显著差异。在逐步递增测试（P = 0.622）或13米/秒速度测试（P = 0.059）中，运动时间不受西地那非给药的影响。
在这些试验中，西地那非并未减轻肺出血或提高与运动表现相关的指标。给予西地那非改变了心血管系统对剧烈运动的适应性，表现为亚最大速度和运动后心率的改变。这些改变对其他运动表现指标的影响并不明显。
