Measurement of ionized calcium in blood platelets with a new generation calcium indicator |
| |
Authors: | G H Rao J D Peller J G White |
| |
Affiliation: | 1. Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 W Stadium Ave, West Lafayette, IN 47907, USA;2. Purdue Institute for Integrative Neuroscience, Purdue University, 207 S Martin Jischke Dr Rm 399, West Lafayette, IN 47907, USA;3. Purdue Institute for Drug Discovery, Purdue University, 720 Clinic Dr, West Lafayette, IN 47907, USA |
| |
Abstract: | Fura 2, a new generation calcium indicator, has a 30 fold brighter fluorescence than Quin 2, shows wavelength shifts upon calcium binding and has a relatively low buffering capacity for free calcium. Quin 2, the most widely used fluorophore, on the other hand, shows no wavelength shifts and has a very high affinity for free calcium. Therefore, we have compared the relative merits of these two fluorophores for monitoring agonist induced alterations in platelet cytosolic calcium. Platelets loaded with Fura 2 showed a significant rise in cytosolic calcium when stirred with agonists such as epinephrine, arachidonate and thrombin, whereas Quin 2 loaded platelets demonstrated a rise in cytosolic calcium only with thrombin stimulation. A rise in agonist induced calcium in Fura 2 loaded platelets was prevented when the cells were exposed first to antagonists such as aspirin or prostaglandin E1. Arachidonate refractory platelets, upon stirring with a single agonist, did not show a significant elevation in cytosolic calcium. However, when refractory platelets were first exposed to epinephrine and then challenged with arachidonate, they revealed a significant elevation in cytosolic calcium. Unlike Quin 2, Fura 2 at the highest concentration tested did not inhibit platelet function. Improved properties of Fura 2 suggest that it may be a useful agent to study agonist induced alterations in cytosolic calcium levels in blood platelets. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|