Abstract
Abstract Two hours after physical stress, Periplaneta americana could be separated into three behavioural categories: normal to hyperactive; torpid with ataxia; and paralysed. At 2 hr, 68 per cent were either torpid or paralysed, at 20 hr, 83 per cent were paralysed. Weight loss was a distinct physiological symptom of stress paralysis: The calculated mean loss was 9·5 mg/hr for torpid insects and 12·4 mg/hr for paralysed cockroaches, losses were four to six times larger than those occurring in starved cockroaches. However, the haemolymph osrnolarities of the three categories showed no appreciable differences. Only starved and paralysed cockroaches showed a noticeable reduction in muscle fibre membrane potentials of the flexor tibia—a mean value below 40 mV for starved insects and a mean value below 50 mV for paralysed insects. Both of these categories consistently showed a lower amplitude for junctional potentials, but paralysed cockroaches showed a much higher incidence of complete failure to neural stimulation. Most muscle fibres of completely paralysed insects lost their sensitivity to direct extracellular stimulation while the loss in sensitivity was less evident in starved cockroaches. Axonal conduction on the crural nerve was not changed by stress, and the spontaneous efferent activity of completely paralysed insects was similar to the pattern of activity for normal cockroaches. Stress seemed to alter the volume and content of the intermyofibral spaces of muscles.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.