In normal dogs, rhIL-11 up-regulates VWF mRNA levels. For 7 consecutive days, rhIL-11 was given to a normal dog. A second normal dog was used as a control. Tissues were harvested, and total RNA was analyzed by Northern blot analysis for the presence of VWF mRNA with the use of canine VWF cDNA as probes. Changes in VWF mRNA were normalized to GAPDH mRNA levels by densitometric quantitation of the autoradiographs. Representative gels are shown for each tissue. Only faint VWF bands appear at baseline, and these increase markedly with rhIL-11 treatment. Results are presented for 5 tissues (left ventricle, right ventricle, atria, aorta, and spleen) as fold increase between treated and untreated animal for the gels shown. No change in VWF mRNA was seen in the homozygous VWD dog treated with rhIL-11 (data not shown).