Structure-function analysis of rhythmogenic inspiratory pre-Bötzinger complex networks in "calibrated" newborn rat brainstem slices.
Inspiratory pre-Bötzinger complex (preBötC) networks remain active in perinatal rodent brainstem slices. Our analysis of (crescendo-like) inspiratory-related population and cellular bursting in novel histologically identified transversal preBötC slices in physiological (3 mM) superfusate [K(+)] revealed: (i) the preBötC extent sufficient for rhythm in thin slices is at most 175 microm. (ii) In 700 microm thick slices with unilaterally exposed preBötC, a <100 microm kernel generates a eupnea-like inspiratory pattern under predominant influence of caudally adjacent structures or thyrotropin-releasing hormone-like transmitters, but a mixed eupnea-sigh-like pattern when influence of rostral structures or substance-P-like transmitters dominates. (iii) Primarily presynaptic processes may underlie inhibition of rhythm by opioids or raising superfusate [Ca(2+)] from lower to upper physiological limits (1-1.5 mM). (iv) High K(+) reverses depression of rhythm by raised Ca(2+), opioids and anoxia. In summary, distinct activity patterns of spatiochemically organized isolated inspiratory networks depend on both an extracellular "Ca(2+)-K(+) antagonism" and slice dimensions. This explains some discrepant findings between studies and suggests use of "calibrated" slices and more uniform experimental conditions.
Ballanyi
Klaus
K
Department of Physiology, University of Alberta, 220 HMRC, Edmonton, AB, Canada T6G 2S2. klaus.ballanyi@ualberta.ca
Ruangkittisakul
Araya
A
D000818:Animals; D000831:Animals, Newborn; D002138:Calibration; D002412:Cations / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D009415:Nerve Net / Q000033:anatomy & histology* / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010507:Periodicity; D051381:Rats; D012119:Respiration / Q000187:drug effects; D012125:Respiratory Center / Q000166:cytology* / Q000502:physiology*; D013329:Structure-Activity Relationship
D002412:Cations