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氢清除法检测视乳头血流

已有 3947 次阅读 2012-12-20 14:48 |个人分类:呼吸氢气|系统分类:科研笔记|关键词:学者| 检测, 生理学, 经典的

氢清除法检测视网膜血流量.pdf

视网膜血流检测是研究视网膜病理生理学的重要手段,目前比较经典的方法是使用激光多谱勒、激光斑点流量、氢清除法、视网膜血管分析、彩色多谱勒等检测方法,过去的方法是采用氢清除法,其中激光斑点流量是唯一无创伤性检测方法,而氢清除法是最经典稳定的方法。这两种方式的结果是否一致是一个值得探讨的问题。本研究采用两种方法,通过药物改变血流,分析两种方法是否一致。结果发现存在比较好的相关性。

本研究中采用经典的氢清除法,是将氢电极直接放入视网膜乳头组织内,通过呼吸10%的氢混合气体(5L/mim),通过氢清除法分析仪确定视网膜血流。这个文章的目的是为说明其新的方法的可靠性和优势。这里有一个经典的氢呼吸后在组织内的改变曲线,这对研究氢的体内变化规律是一个非常重要的参考信息。我们可以看出当动物呼吸5分钟后,组织内的氢浓度迅速升高,从理论上分析,这个浓度并没有达到饱和,如果继续呼吸,则浓度可以继续增加。更重要的信息是,当停止呼吸后,氢浓度并没有立刻下降,其原因是呼吸后血液中的氢浓度可以维持一段短的时间,然后氢浓度以迅速下降,但速度逐渐降低,到停止呼吸10分钟,氢浓度已经下降到最大值的10%以下。这个变化规律很有代表性,分析呼吸氢治疗疾病的原因是需要考虑作用时间,这是非常具有参考价值的。

Abstract

The aim of this study was to verify the correlation between mean blur rate (MBR) obtained with CCD-equipped laser speckle flowgraphy (LSFG) and capillary blood flow (CBF) obtained by the hydrogen gas clearance method in rabbit optic nerve head (ONH). Using Japanese white rabbits under systemic anesthesia, a hydrogen electrode was inserted an area of the ONH free from superficial capillaries. MBR was measured with LSFG near the hydrogen electrode. CBF and MBR were measured in the range of 32.4-83.5 mL/min/100 g and 3.5-6.0, respectively. MBR and CBF were significantly correlated (r = 0.73, P<0.01, n = 14). After inhalation of carbon dioxide (CO2) or intravenous administration of endothelin-1 (ET-1), MBR and CBF were changed in the relative range of 0.74-1.27 and 0.76-1.35, respectively. The relative changes in MBR and CBF induced by CO2 and ET-1 were also significantly correlated (r = 0.67, P<0.01). The current results suggest that MBR may correlate with CBF and also change with CBF, as an index of blood flow in the ONH, linearly.

Mydriasis was induced by topical tropicamide (Mydrin®-M ophthalmic solution 0.4%, Santen Pharmaceutical Co. Ltd., Osaka, Japan). Animals were anesthetized by intraperitoneal injection of 0.8 mg/kg urethane at 0.4 g/mL (Nakalai, Kyoto, Japan) and additional intramuscular injection of 0.1 mg/kg urethane as necessary. Topical anesthesia was induced by topical oxybuprocaine (Benoxil® ophthalmic solution 0.4%, Santen Pharmaceutical Co. Ltd.). The CBF in the ONH was measured by the hydrogen gas clearance method as previously reported (Sugiyama et al., 1996). A hydrogen electrode (Cat.# OA211-013, platinum needle with a 0.7-mm long and 0.1-mm diameter Pt-Ir tip, Unique Medical Co., Ltd., Tokyo, Japan) was inserted into a lower portion of the ONH with no visible surface vessels through the vitreous body from the pars plana using a vitrectomy lens. The reference electrode was subcutaneously fixed on the head. After the inhalation of 10% hydrogen gas by a mask at 5 L/min for 5 min, CBF was calculated with the hydrogen concentration half-life (T1/2) using a hydrogen clearance flow meter (model MDH-D1, Unique Medical Co., Ltd.). As shown in Fig.1A, since the clearance curve is approximately mono-exponential, the hydrogen concentration was plotted into logarithm to get half-life (T1/2) for calculation. Specifically in the current study, the linearity of hydrogen clearance in logarithm was found beforehand to be the highest at 1 to 2 min after stopping hydrogen inhalation (Fig.1B), therefore we adopted the half-life there to calculate CBF as 69.3/ T1/2 (mL/min/100g).

 



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