Time-dependent changes in spontaneous respiratory activity in turtle brainstems in vitro.
Our goal was to determine whether time-dependent changes in respiratory motor output in vitro could be minimized by altering bath solution composition. Adult turtle brainstems were bathed in standard solution, nutrient-rich Dulbecco's Eagle media (100 or 25% concentration), or standard solution with phenylbiguanide (PBG, 5-HT3 agonist which increases respiratory drive). Except for a 63% frequency increase in PBG solution, hypoglossal bursts were unaltered within 100 min of observation. Respiratory activity was abolished within 7 h in 100% Dulbecco's compared with a mean of 24-31 h in other test solutions. At 12 h, burst frequency decreased faster in standard solution and 25% Dulbecco's (-0.28+/-0.07 and -0.13+/-0.05 bursts/h, respectively) compared with PBG solution (-0.09+/-0.04 bursts/h); amplitude declined at approximately 2%/h in all solutions. The tendency for episodic discharge decreased gradually in standard solution, but was eliminated in 25% Dulbecco's and PBG solution. Certain bath solutions may minimize time-dependent frequency reductions but may also cause breathing pattern changes.
Wilkerson
J E R
JE
Center for Neuroscience, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA. wilkersj@svm.vetmed.wisc.edu
Wenninger
M R
MR
Mitchell
G S
GS
Johnson
S M
SM
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D012119:Respiration / Q000187:drug effects; D016897:Respiratory Burst / Q000187:drug effects; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors; D014426:Turtles
D001645:Biguanides; D003470:Culture Media; D017366:Serotonin Receptor Agonists; C008846:phenyl biguanide