[Effect of insulin on the myocardium of the active, hibernating and wakening ground squirrel Citellus undulatus].
The effect of insulin (0.1-100 nM) on isometric force of contraction in isolated ground squirrel papillary muscle was investigated. In summer, autumn and winter active animals, insulin had a negative inotropic effect on papillary muscles, decreasing the amplitude of contraction by about 30% of the control value. In some cases, predominantly in the summer group of animals, insulin produced different effects on contractility: low doses (0.1-0.5 nM) caused a transient activation of isometric contraction by about 10-15% of control, whereas high doses produced a negative inotropic effect by about 30% of the control level. During deep hibernation (at 5-6 degrees C of heart temperature) and during arousal from hibernation (from 3 to 20 degrees C), insulin had no significant effect on contractility. Opposite inotropic effects of insulin at concentrations of 0.1-50 nM were found during arousal: from 26 to 31 degrees C of heart temperature--a positive inotropic effect by about 20-25% of control, and from 32 to 36 degrees C--a negative one by about 30-40% of the control value.
Nakipova
O V
OV
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
Gaĭnullin
R Z
RZ
Andreeva
L A
LA
Safronova
V G
VG
Kosarskiĭ
L S
LS
Kolaeva
S G
SG
Solomonov
N G
NG
Kukushkin
N I
NI
D000818:Animals; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006605:Hibernation; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology; D012589:Sciuridae / Q000502:physiology*; D012621:Seasons; D014851:Wakefulness
D007328:Insulin