Using heart rate to predict energy expenditure in large domestic dogs.

The aim of this study was to establish heart rate as a measure of energy expenditure in large active kennel dogs (28 ± 3 kg bw). Therefore, the heart rate (HR)-oxygen consumption (V˙O2) relationship was analysed in Foxhound-Boxer-Ingelheim-Labrador cross-breds (FBI dogs) at rest and graded levels of exercise on a treadmill up to 60-65% of maximal aerobic capacity. To test for effects of training, HR and V˙O2 were measured in female dogs, before and after a training period, and after an adjacent training pause to test for reversibility of potential effects. Least squares regression was applied to describe the relationship between HR and V˙O2. The applied training had no statistically significant effect on the HR-V˙O2 regression. A general regression line from all data collected was prepared to establish a general predictive equation for energy expenditure from HR in FBI dogs. The regression equation established in this study enables fast estimation of energy requirement for running activity. The equation is valid for large dogs weighing around 30 kg that run at ground level up to 15 km/h with a heart rate maximum of 190 bpm irrespective of the training level.

Isolation, partial purification and in vitro characterization of osteogenic inhibitory protein.

A noncollagenous protein has been extracted and partially purified from adult cortical bone. This protein copurifies with another bone matrix protein, bone morphogenetic protein, until treatment with nonionic detergents. Characterization of the biological activity of this new protein has demonstrated it to be a potent osteogenic inhibitor in vitro. The inhibitor antagonizes the chondrogenic activity of devitalized, demineralized bone matrix as well as the activity of soluble bone morphogenetic protein. Bone matrix induced collagen and glycosaminoglycan synthesis are both inhibited in the presence of various concentrations of the osteogenic inhibitory protein. Inhibition of collagen synthesis required the presence of osteogenic inhibitory protein from the initiation of the tissue culture while glycosaminoglycan synthesis could be inhibited at any stage of differentiation. We postulate that this osteogenic inhibitory protein is essential in normal homeostatic bone metabolism, perhaps acting directly on bone morphogenetic protein.