ASGSB 2002 Abstracts - SIMULATED MICROGRAVITY’S EFFECT ON THE CONTRACTILE ABILITY OF DEVELOPING CHICK HEART TISSUE EXPLANTS

ASGSB 2002 Annual Meeting Abstracts

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SIMULATED MICROGRAVITY’S EFFECT ON THE CONTRACTILE ABILITY OF DEVELOPING CHICK HEART TISSUE EXPLANTS. Krista L. Todd and Darrell Wiens, Dept of Biology, University of Northern Iowa.

Previous in vitro studies have shown that gravitational effects may disturb the cytoskeletal / extracellular matrix interaction, alter organo-genesis, and result in the development of a morphologically intact, yet non-contracting heart. Two of the proteins that play an important role in this interaction are paxillin and b1-integrin. We have examined the effect of simulated microgravity on the expression and distribution of these proteins in an attempt to explain the functional difference. Pre-cardiac tissue explants from HH stages 4 – 7⁺ were exposed to a zero sum vector force environment by vertical rotation in a 10.0 ml HARV bioreactor for 19 hours during development. We observed development of contractions in only 11 of 45 (24%), even less than in previous work. Forty-six of 54 (84%) of stationary or horizontally-rotated control explants contracted.

We then immunostained the explants with paxillin and b1-integrin monoclonal antibodies to reveal areas of the explants expressing these proteins. It was observed in whole explants and 7mm sections that both proteins were localized to the perimeter, showing a solid staining area, a mottled area, and an area devoid of stain . Color threshold image analysis indicated no significant difference from control in percent total area of paxillin staining. However, initial results indicate integrin is less abundant in those exposed to microgravity during development.

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