Key result
Ouabain and K+-free solutions transiently increase vascular resistance via external Ca2+ influx.
Why the study?
The study aimed to investigate changes in vascular resistance of the perfused rat-tail artery in response to ouabain-containing and/or K+-free solutions and the role of external Ca2+ in these responses.
Caution against extrapolating rat-tail findings to patients; extends mechanistic insight into Ca2+-dependent vascular responses to Na/K-ATPase inhibition.
The changes in the resistance of the perfused ventral rat-tail artery resulting from exposure of the tissue to ouabain-containing and/or K+-free physiological salt solution were studied. In each case, there was an increase in the vascular resistance which was not sustained. The response of the arterial wall to the above stimuli was abolished in the absence of external Ca2+. In contrast to the delayed response of the wall to either ouabain-containing or K+-free solution, an almost instantaneous rise in the resistance was observed if the two stimuli were combined, though the rate of loss of the tissue K+ was not accelerated significantly under these experimental conditions. The tension developed in K+-free solution was relieved almost instantaneously upon readmittance of external potassium.
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Friedman et al. (1973) studied this question. Ouabain-containing and/or K+-free physiological salt solution vs. Normal physiological salt solution was evaluated on Vascular resistance. Exposure of the perfused rat-tail artery to ouabain-containing or K+-free solution caused a transient increase in vascular resistance that was abolished in the absence of external Ca2+.
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