Current pulses involving chloride and potassium efflux relieve excess pressure in Pelvetia embryos.

Embryos of Pelvetia fastigiata De Toni respond to sudden decreases in osmotic pressure by driving characteristic current pulses through themselves. One group of pulses occurs immediately after the pressure decrease and another often follows about 1 h later. While there is a measurable response to decreases as small as 3%, a far larger response occurs above a threshold change of 8-10%. These pulses involve an efflux of Cl(-) and K(+) ions which approximately restores the original turgor pressure.