We introduce a compact and portable photometric system for measurements of the calcium dynamics in cells. The photometer is designed for applications in centrifuges or in zero gravity environment and thus extremely compact and reliable. It operates with the calcium-sensitive dye Indo-1. The excitation wavelength of 345 nm is generated by frequency doubling of a laser diode. Two compact photomultiplier tubes detect the fluorescent emission. The electronics provide the sensitivity of photon counting combined with simultaneous measurement of the temperature, of air pressure, and of gravitational force. Internal data storage during the experiment is possible. A newly developed cell chamber stabilizes the cell temperature to 37.0±0.1 °C and includes a perfusion system to supply the cells with medium. The system has a modular setup providing the possibility of changing the light source and detectors for investigation of ions other than calcium. Measurements of the intracellular calcium concentration are based on a comprehensive calibration of our system. First experiments show that the calcium dynamics of osteosarcoma cells stimulated by parathyroid hormone is observable.
The reaction of bone cells after mechanical stimulation is a key issue in understanding the origins of osteoporosis. We investigate mechanical stimulation of osteoblasts and their reaction with a new combination of an atomic force apparatus with a fluorescence microscope. First measurements on the mechanically induced calcium response of osteoblasts are presented. The average threshold force for stimulation is 300nN and the dynamics of the calcium response is in the several tens of seconds range.
The reaction of bone cells after mechanical stimulation is a key issue in understanding the origins of osteoporosis. We investigate mechanical stimulation of osteoblasts and their reaction with a new combination of an atomic force apparatus with a fluorescence microscope. First measurements on the mechanically induced calcium response of osteoblasts are presented. The average threshold force for stimulation is 300nN and the dynamics of the calcium response is in the several tens of seconds range.
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