Rabbit atrial myocardium in hypoxic conditions: rate dependent variation of contraction
Schüttler, K.; Nilius, B.; Boldt, W.
Biomedica Biochimica Acta 43(4): 473-484
1984
ISSN/ISBN: 0232-766X PMID: 6487278 Document Number: 223716
The dependence of contraction, in the atrial myocardium, on the stimulation pattern was studied in normoxic and hypoxic conditions. Isotonic contractions were measured from left atrial muscle strips of the rabbit. At rapid stimulation, hypoxia produced a negative inotropic effect, which disappeared at slower stimulation and became a positive inotropic one. The potentiation of a 1st beat after a pause in stimulation was enhanced by hypoxia, because the contractions were more strongly depressed at steady state than after a pause. At all pacing patterns, the relative maximum rate of shortening and re-lengthening were independent of the O2 supply. After application of epinephrine in hypoxia, they were enhanced, and so was peak shortening. An impaired or altered function of the sarcolemma was suggested only under the degrees of hypoxia chosen.