pSpectroscopic Casup2+/sup-indicators are thought to report values of free intracellular Casup2+/sup concentration ([Casup2+/sup]subi/sub) that may differ from unperturbed values because they add to the buffering capacity of the tissue. To check this for the heart we have synthesized a new sup19/supF-labelled NMR Casup2+/sup indicator, 1,2-bis-[2-bis(carboxymethyl)amino-4,5-difluorophenoxy]ethane (‘4,5FBAPTA’), with a low affinity (iK/isubd/sub 2950 nM). The new indicator and four previously described sup19/supF-NMR Casup2+/sup indicators 1,2-bis-[2-(1 - carboxyethyl)(carboxymethyl)amino - 5 - fluorophenoxy]ethane (‘DiMe-5FBAPTA’), 1,2-bis-[2-(1-carboxyethyl)(carboxymethyl)amino-4-fluorophenoxy]ethane (‘DiMe-4FBAPTA’), 1,2-bis-[2-bis(carboxymethyl)amino-5-fluorophenoxy]ethane (‘5FBAPTA’) and 1,2-bis-[2-bis(carboxymethyl)amino-5-fluoro-4-methylphenoxy]ethane (‘MFBAPTA’), with dissociation constants for Casup2+/sup ranging from 46 to 537 nM, have been used to measure [Casup2+/sup]subi/sub, over the range from less than 100 nM to more than 3 iμ/iM, in Langendorff-perfused ferret hearts (30 °C, pH 7.4, paced at 1.0 Hz) by sup19/supF-NMR spectroscopy. Loading hearts with indicators resulted in buffering of the Casup2+/sup transient. The measured end-diastolic and peak-systolic [Casup2+/sup]subi/sub were both positively correlated with indicator iK/isubd/sub. The positive correlations between indicator iK/isubd/sub and the measured end-diastolic and peak-systolic [Casup2+/sup]subi/sub were used to estimate the unperturbed end-diastolic and peak-systolic [Casup2+/sup]subi/sub by extrapolation to iK/isubd/sub = 0 (diastolic) and to iK/isubd/sub = ∞ (systolic) respectively. The extrapolated values in the intact beating heart were 161 nM for end-diastolic [Casup2+/sup]subi/sub and 2650 nM for peak-systolic [Casup2+/sup]subi/sub, which agree well with values determined from single cells and muscle strips./p
展开▼
机译：>光谱学上的Ca 2 + 指标被认为报告了游离细胞内Ca 2 + 浓度的值（[Ca 2 + ] i ）可能与不受干扰的值有所不同，因为它们增加了组织的缓冲能力。为了检查心脏，我们合成了新的 19 F标记的NMR Ca 2 + 指示剂1,2-双-[2-双（羧甲基）氨基- 4,5-二氟苯氧基]乙烷（'4,5FBAPTA'），具有低亲和力（ K d 2950 nM）。新的指示剂和四个先前所述的 19 F-NMR Ca 2 + 指示剂1,2-双-[2-（1-（羧乙基）（羧甲基）氨基]-5-氟苯氧基]乙烷（'DiMe-5FBAPTA'），1,2-双-[2-（1-羧乙基）（羧甲基）氨基-4-氟苯氧基]乙烷（'DiMe-4FBAPTA'），1,2-双-[ 2-双（羧甲基）氨基-5-氟苯氧基]乙烷（'5FBAPTA'）和1,2-双-[2-双（羧甲基）氨基-5-氟-4-甲基苯氧基]乙烷（'MFBAPTA'）， Ca 2 + 的解离常数范围为46到537 nM，已用于测量[Ca 2 + ] i ，范围为 19 F-NMR光谱法在灌注Langendorff的雪貂心脏（30°C，pH 7.4，以1.0 Hz调节）中，小于100 nM至大于3 μM 。用指示剂加载心脏导致Ca 2 + 瞬变的缓冲。舒张末期和收缩期峰值[Ca 2 + ] i 与指标 K d 。指标 K d 与测得的舒张末期和收缩期峰值[Ca 2 + ] i 通过外推到 K d <来估计舒张末期舒张末期和收缩期高峰[Ca 2 + ] i / sub> = 0（舒张压）和 K d =∞（收缩压）。完整的跳动心脏中的舒张末期[Ca 2 + ] i 的外推值是161 nM，而收缩期高峰[Ca 2+ < / sup>] i ，与单细胞和肌肉条确定的值非常吻合。
展开▼
