McKeever K H, Malinowski K
Department of Animal Science, Cook College, Rutgers-State University of New Jersey, New Brunswick 08901, USA.
Equine Vet J Suppl. 1999 Jul(30):561-6. doi: 10.1111/j.2042-3306.1999.tb05284.x.
Six young (mean + s.e., 5.3 +/- 0.8 years, 445 +/- 13 kg bwt) and 6 old (22.0 +/- 0.4 years, 473 +/- 18 kg bwt) Standardbred and Thoroughbred mares were used to test the hypothesis that age would alter the endocrine response to exercise. All of the mares were unconditioned but accustomed to the laboratory, to standing quietly and running on a treadmill, and to the standardised incremental exercise test (SET) used in the experiment. Two weeks prior to the experiment, each horse underwent a SET to determine maximal oxygen uptake (VO2max) and the speeds to be used in the actual experiment. A second graded exercise test (GXT) was performed without instrumentation for the measurement of plasma renin activity (PRA) and the plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), aldosterone (ALDO), and endothelin-1 (ET-1). Blood samples (30 ml) were collected at rest and at the end of each one minute step of the exercise test. Plasma concentrations of hormones were measured using radioimmunoassay kits. There were no differences (P > 0.05) between old vs. young mares for resting PRA (2.2 +/- 0.3 vs. 1.5 +/- 0.3 ng/ml/h), or the plasma concentrations of ANP (10.0 +/- 0.9 vs. 10.7 +/- 0.6 pg/ml); AVP (0.7 + 0.7 vs. 1.4 +/- 0.4 pg/ml); ALDO (39.2 +/- 10.3 vs. 22.7 +/- 4.6 pg/ml); or ET-1 (0.23 +/- 0.04 vs. 0.18 +/- 0.03 pg/ml). Exercise significantly increased PRA and the concentrations of ANP, AVP, and ALDO in both groups of horses; however, ET-1 was not altered (P > 0.05) by exercise in either group. There were differences (P < 0.05) between means obtained from the old and young groups for PRA (5.4 +/- 0.6 vs. 3.9 +/- 0.8 ng/ml/h and the concentrations of ANP (14.5 +/- 2.3 vs. 26.5 +/- 9.0 pg/ml), AVP (13.6 +/- 0.3 vs. 26.1 +/- 13.9 pg/ml, and ALDO (76.8 +/- 22.0 vs. 41.5 +/- 4.9 pg/ml) measured in samples obtained at the speed eliciting VO2max. These data suggest that older horses have an age-altered endocrine response to exercise.
选用6匹年轻（平均年龄±标准误，5.3±0.8岁，体重445±13千克）和6匹年老（22.0±0.4岁，体重473±18千克）的标准赛马和纯种母马，以检验年龄会改变运动的内分泌反应这一假说。所有母马均未经过训练，但已习惯实验室环境、习惯安静站立和在跑步机上奔跑，以及习惯实验中使用的标准化递增运动试验（SET）。在实验前两周，每匹马都进行了一次SET，以确定最大摄氧量（VO2max）以及实际实验中要使用的速度。在无测量血浆肾素活性（PRA）、心房利钠肽（ANP）、精氨酸加压素（AVP）、醛固酮（ALDO）和内皮素-1（ET-1）血浆浓度仪器的情况下，进行了第二次分级运动试验（GXT）。在静息状态和运动试验每一分钟阶段结束时采集血样（30毫升）。使用放射免疫分析试剂盒测量激素的血浆浓度。年老与年轻母马在静息PRA（2.2±0.3对1.5±0.3纳克/毫升/小时）或ANP血浆浓度（10.0±0.9对10.7±0.6皮克/毫升）、AVP（0.7±0.7对1.4±0.4皮克/毫升）、ALDO（39.2±10.3对22.7±4.6皮克/毫升）或ET-1（0.23±0.04对0.18±0.03皮克/毫升）方面无差异（P>0.05）。运动显著增加了两组马匹的PRA以及ANP、AVP和ALDO的浓度；然而，两组中运动均未改变ET-1（P>0.05）。在达到VO2max的速度下采集的样本中测量的PRA（5.4±0.6对3.9±0.8纳克/毫升/小时）、ANP浓度（14.5±2.3对26.5±9.0皮克/毫升）、AVP（13.6±0.3对26.1±13.9皮克/毫升）和ALDO（76.8±22.0对41.5±4.9皮克/毫升），年老组和年轻组的均值之间存在差异（P<0.05）。这些数据表明，年老马匹对运动的内分泌反应随年龄而改变。
