this need not imply that the pressor substance , if it is a single definite substance developed in the shed blood , exerts no action on the smooth muscle of the intestine and uterus preparations , but merely that its action on these objects is masked by the general action of the serum and plasma , so that in the presence of the other constituents common to serum and plasma , its effect is inconspicuous or not to be detected at all , while on the blood vessel preparations , especially the artery rings , the effect of the pressor substance is the dominant one , and the general action of the serum and plasma is feeble or undetectable .
C0229671
serum
C0032105
plasma