Ouabain susceptibility of heart muscle of the house musk shrew, an insectivore: a comparison with the rat, guinea pig and rhesus monkey.

The susceptibility to ouabain of the heart muscle of the house musk shrew (Suncus murinus), an insectivore, was investigated by means of in vitro experimentation, and compared with the rat, guinea pig, and rhesus monkey. Contraction of the electrically driven heart muscles of all species slowly increased following application of ouabain. The shrew was approximate 100-fold more sensitive than the rat and 10-fold less than the guinea pig and rhesus monkey. Only the rat heart preparation that was arrested by the highest concentration of ouabain could be restored by a few washings with medium. The pharmacological characteristics of the shrew differ from those of the rat and were comparatively similar to those of the guinea pig and rhesus monkey.