Kapitola J, Zák J, Lacinová Z, Justová V
Laboratory for Endocrinology and Metabolism, Charles University, Prague, Czech Republic.
Physiol Res. 2000;49 Suppl 1:S101-6.
So far it is not known whether the growth hormone (GH) has an effect on the local blood circulation in bones. Using male rats we studied the local blood circulation in the tibia and the distal end of the femur (by means of the uptake of 85Sr-microspheres), the density and ash weight of the tibia, the urinary excretion of pyridinoline (PD) and deoxypyridinoline (DPD) as an indicator of bone resorption and the blood levels of IGF-I after the administration of human GH (4 mg/kg s.c. daily for 4 weeks) and/or bisphosphonate pamidronate (Aredia, CIBA-Geigy, administered in the dose of 3 mg/kg i.p. on day 1, 2, 9 and 10). The rats were divided into four groups: 1. controls, 2. GH, 3. pamidronate, 4. GH plus pamidronate. After the administration of GH, we observed a significant increase in bone blood flow (and in the uptake of 85Sr-microspheres), a decrease in the density and ash weight of the tibia and increased urinary excretion of PD and DPD; IGF-I levels in the blood were non-significantly elevated. Simultaneously administered pamidronate inhibited all significant effects of GH and it also decreased the IGF-I levels in rats treated with GH. After the administration of pamidronate itself the bone density and ash weight of the tibia were increased and urinary DPD excretion was decreased. In view of the known vascular effects of IGF-I, we assume that the increase in bone blood flow after the administration of GH and its reduction after simultaneous administration of pamidronate could be mediated by the changes of IGF-I blood levels, although the effect of pamidronate on IGF-I is still not clear. Regarding the role of blood circulation in rat bones, we consider that our present results are further evidence for the relationship between the blood circulation in bones and bone resorption, although these results do not show how active is bone blood circulation in the regulation of bone tissue metabolism.
迄今为止，尚不清楚生长激素（GH）是否对骨骼局部血液循环有影响。我们使用雄性大鼠，研究了胫骨和股骨远端的局部血液循环（通过85Sr-微球体摄取法）、胫骨的密度和灰重、吡啶啉（PD）和脱氧吡啶啉（DPD）的尿排泄量作为骨吸收指标，以及在给予人生长激素（4mg/kg皮下注射，每日一次，共4周）和/或双膦酸盐帕米膦酸盐（阿可达，汽巴-嘉基公司，第1、2、9和10天腹腔注射，剂量为3mg/kg）后IGF-I的血药浓度。大鼠被分为四组：1. 对照组；2. GH组；3. 帕米膦酸盐组；4. GH加帕米膦酸盐组。给予GH后，我们观察到骨血流量显著增加（以及85Sr-微球体摄取增加）、胫骨密度和灰重降低、PD和DPD尿排泄增加；血中IGF-I水平无显著升高。同时给予帕米膦酸盐可抑制GH的所有显著作用，并且还降低了接受GH治疗的大鼠的IGF-I水平。给予帕米膦酸盐本身后，胫骨的骨密度和灰重增加，尿DPD排泄减少。鉴于已知IGF-I的血管作用，我们推测给予GH后骨血流量增加以及同时给予帕米膦酸盐后骨血流量减少可能是由IGF-I血药浓度的变化介导的，尽管帕米膦酸盐对IGF-I的作用仍不清楚。关于大鼠骨骼中血液循环的作用，我们认为我们目前的结果进一步证明了骨骼血液循环与骨吸收之间的关系，尽管这些结果并未表明骨血液循环在调节骨组织代谢方面有多活跃。
