AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 4 670-R679, Copyright © 1986 by American Physiological Society
Cardiac input to medullary reticular formation: neuronal responses to CAO
R. W. Blair
Responses of 46 medullary reticular neurons to coronary arterial occlusions
(CAO) of the left anterior descending (LAD) and left circumflex (CX)
coronary arteries were determined in chloralose-anesthetized cats paralyzed
with pancuronium. Extracellular potentials were recorded from individual
neurons, in the medial reticular formation, responsive to electrical
stimulation of cardiopulmonary sympathetic afferents. CAO responses were
characterized by one of three patterns. Cell activity changed during
myocardial ischemia (IS response). Fifteen neurons were excited during
ischemia (9 +/- 2.8 to 15 +/- 3.2 spikes/s for CX occlusion and 10 +/- 3.0
to 17 +/- 4.7 spikes/s for LAD occlusion), and two were inhibited (8 +/-
3.0 to 4 +/- 3.0 spikes/s). Cell activity changed at the onset or release
of occlusion and rapidly adapted (ON response). Four cells were excited at
the onset of LAD occlusion (2 +/- 1.4 to 10 +/- 6.0 spikes/s), 9 cells were
excited at onset of CX occlusion (5 +/- 2.5 to 16 +/- 5.6 spikes/s), and 1
cell decreased its rate at onset of CX occlusion. A combination of ON and
IS responses occurred in five cells (ON-IS response). Overall, 24 neurons
exhibited at least one of these responses, and 22 cells were unaffected by
CAO. Thirty neurons were tested for responses to CAO of CX and LAD; neurons
most often exhibited different patterns of responses to CAO of each artery.
Thirty-one of 34 cells tested exhibited qualitatively, but often not
quantitatively, similar responses to cardiac ischemia and to application of
bradykinin to epicardium of free wall of left ventricle. Results indicate
that medullary neurons often respond differentially to occlusion of
different coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)
