AJP - Cell Physiology, Vol 249, Issue 5 522-C526, Copyright © 1985 by American Physiological Society
System for automatic activation of skinned muscle fibers
Y. C. Chiu, J. Quinlan and L. E. Ford
A system is described for automatically changing the solutions surrounding
skinned muscle fibers at a controlled temperature. The system consists of a
complex muscle chamber and solenoid valve-controlled vacuum-driven syringe
pumps. The chamber has a muscle trough, a conduit for circulating coolant,
and channels for precooling solutions. After traveling through the cooling
channels, the solutions are injected into one end of the muscle trough and
removed by suction at the other. The volume of the trough (approximately 40
microliter) is kept as low as possible to minimize the amount of solution
required for complete solution exchange (approximately 400 microliter).
Solution changes are complete within 400 ms. The timing of the sequence of
solution changes is precisely controlled by digital timers that activate
the solenoid valves of the pumps. By exposing the fibers briefly to a high
concentration of free calcium and then changing to a buffered calcium
solution, it is possible to achieve steady tension levels in 1-2 s, even
when partially activating the fibers. Such rapid partial activation is
possible because the exposure to free calcium can be precisely timed. The
timers also allow the solution changes to be synchronized with other
perturbations.
