Embryogenesis in the Presence of Blockers of Mechanosensitive Ion Channels

Certain developmental events are thought to be controlled by mechanical tension, but the nature of the transduction mechanism for sensing and responding to tension changes is unknown. A good candidate for such a sensing system would be stretch-activated (SA) ion channels, a type of mechanosensitive (MS) ion channel found in many preparations including the oocytes or embryos of ascidians, fish, and amphibians. To test the hypothesis that SA channel activation is important for early embryogenesis, we treated amphibian and ascidian eggs and embryos with inhibitors of MS ion channels. Xenopus laevis eggs and embryos were treated with gadolinium (Gd³⁺) concentrations up to 100 times the K_d for SA channel inhibition. Boltenia villosa eggs and embryos were exposed to three agents (Gd³⁺, tubocurarine, and gallamine) which are known to block SA channels in other organisms. None of these drugs interfered with morphogenesis in a manner that would suggest SA channel activity is critical to early embryogenesis.