... of the mesoglea, both in isolated samples and in an intact bell preparation. Using this information, we calculated the stiffness of the fibres of the hydromedusa Polyorchis penicillatus ,which we found to be approximately 0.9 MPa, similar in magnitude to other species. This value is two orders of magnitude more...

[email protected] ) 31 7 2001 © The Company of Biologists Limited 2001 2001 calcium stores excitation–contraction coupling jellyfish Polyorchis penicillatus caffeine CaATPase. Muscle contraction is initiated by an increase in the intracellular free calcium concentration...

...Nikita G. Grigoriev; J. David Spafford; Warren J. Gallin; Andrew N. Spencer ABSTRACT The S4 segment of the jellyfish ( Polyorchis penicillatus ) Shaker channel jShak1 contains only six positively charged motifs. All other Shaker channels, including the jellyfish Shaker channel jShak2, have seven...

...J. David Spafford; Nikita G. Grigoriev; Andrew N. Spencer ABSTRACT The Na + current of ‘swimming motor neurones’ in the hydromedusan Polyorchis penicillatus was tetrodotoxin-insensitive. The local anaesthetics lidocaine and procainamide caused partial, non use-dependent blockade of the Na + channel...

...Jun-Mo Chung; Andrew N. Spencer ABSTRACT Recent studies have shown that nerve-rich tissues in the margin of Polyorchis penicillatus (Eschscholtz), one of the hydromedusae, contain dopamine. The present experiments were conducted to determine the physiological action of dopamine at the cellular...