TY - JOUR
T1 - Effect of cooling on vascular smooth muscle from the thirteen-lined ground squirrel
AU - Harker, Christian T.
AU - Webb, R. Clinton
N1 - Funding Information:
Received May 23, 1986; accepted October 21, 1986. r These studies were supported by a grant from the National Institutes of Health (HL-27020). R.C.W. is a recipient of a Research Career Development Award from the National Institutes of Health (HL-00813).
PY - 1987/2
Y1 - 1987/2
N2 - Peripheral vascular resistance in the ground squirrel (Spermophilus tridecemlineatus) increases when the animal enters hibernation. The goals of this study were (1) to determine if a change in vascular reactivity contributes to this hemodynamic response, and (2) to compare the effects of temperature on vascular responsiveness in a hibernator (ground squirrel) and a nonhibernating mammal (rat). Helically cut strips of aortae and femoral arteries were mounted in organ chambers (37 °C) and isometric contractions were recorded. The arteries were made to contract in response to exogenous norepinephrine (5.9 × 10- 7 M). Cooling the organ chamber (11 °C) potentiated contractions to norepinephrine (5-15% increase) in ground squirrel femoral arteries but depressed those (80-100% decrease) in ground squirrel aortae and rat aortae and femoral arteries. Contractions in response to depolarizing concentrations of potassium in ground squirrel femoral arteries were depressed by cooling (11 °C), suggesting that the augmented response to norepinephrine at low temperature is specific. Treatment with indomethacin, propanolol, and ouabain did not alter the potentiating effect of temperature on contractions to norepinephrine in ground squirrel femoral arteries. Apparently, the potentiation is not related to prostaglandins generated in the vascular wall, to blockade of β-adrenergic receptors, nor to inhibition of the electrogenic sodium pump. The observations are consistent with the hypothesis that a change in vascular responsiveness contributes to the regional control of blood flow in hibernation. This adaptive response is specific in that it does not occur in the aorta of the ground squirrel and the response is not present in the vasculature of the rat, a nonhibernating mammal.
AB - Peripheral vascular resistance in the ground squirrel (Spermophilus tridecemlineatus) increases when the animal enters hibernation. The goals of this study were (1) to determine if a change in vascular reactivity contributes to this hemodynamic response, and (2) to compare the effects of temperature on vascular responsiveness in a hibernator (ground squirrel) and a nonhibernating mammal (rat). Helically cut strips of aortae and femoral arteries were mounted in organ chambers (37 °C) and isometric contractions were recorded. The arteries were made to contract in response to exogenous norepinephrine (5.9 × 10- 7 M). Cooling the organ chamber (11 °C) potentiated contractions to norepinephrine (5-15% increase) in ground squirrel femoral arteries but depressed those (80-100% decrease) in ground squirrel aortae and rat aortae and femoral arteries. Contractions in response to depolarizing concentrations of potassium in ground squirrel femoral arteries were depressed by cooling (11 °C), suggesting that the augmented response to norepinephrine at low temperature is specific. Treatment with indomethacin, propanolol, and ouabain did not alter the potentiating effect of temperature on contractions to norepinephrine in ground squirrel femoral arteries. Apparently, the potentiation is not related to prostaglandins generated in the vascular wall, to blockade of β-adrenergic receptors, nor to inhibition of the electrogenic sodium pump. The observations are consistent with the hypothesis that a change in vascular responsiveness contributes to the regional control of blood flow in hibernation. This adaptive response is specific in that it does not occur in the aorta of the ground squirrel and the response is not present in the vasculature of the rat, a nonhibernating mammal.
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U2 - 10.1016/0011-2240(87)90009-5
DO - 10.1016/0011-2240(87)90009-5
M3 - Article
C2 - 3816289
AN - SCOPUS:0023284630
SN - 0011-2240
VL - 24
SP - 74
EP - 81
JO - Cryobiology
JF - Cryobiology
IS - 1
ER -