EFFECT OF HAND HEATING BY A WARM AIR BOX ON O2 CONSUMPTION OF THE CONTRALATERAL ARM

Arterialization of venous blood is often used in studying forearm metabolism. Astrup et al. [Am. J. Physiol. 255 (Endocrinol. Metab. 18): E572-E578, 1988] showed that heating of the hand by a warming blanket caused a redistribution of blood flow in the contralateral arm and thus introduced errors in forearm skeletal muscle flux calculations. The present study was undertaken to investigate how hand heating by a warm air box (60-degrees-C) would affect metabolism and blood flow in the contralateral arm before and during 3 h after a glucose load. Eleven healthy volunteers (5 males, 6 females) underwent an oral glucose tolerance test (70 g) on two different occasions, one test with and one without heating of the contralateral hand, in random order. Heating the hand for 30 min before glucose intake did not affect skin temperature, rectal temperature, deep venous oxygen saturation, forearm blood flow, or oxygen consumption of forearm skeletal muscle. Although, after the glucose load, heating significantly increased forearm blood flow (P < 0.05), the integrated response after glucose was not significantly different between control and heating experiments [67 +/- 43 and 117 +/- 41 (SE) ml/100 ml tissue]. With both conditions, there was an increase in skin temperature (P < 0.001, integrated response control: 369 +/- 79 and heating: 416 +/-203-degrees-C) and oxygen consumption of forearm muscle (control: 290 +/- 73, P < 0.05 and heating: 390 +/- 130-mu-mol/100 ml, P < 0.05) after glucose intake. These responses did not significantly differ between the conditions. Also, there were no significant differences in the other variables after the glucose load between the control and heating experiment. In conclusion, heating by a warm air box has no effect on deep venous oxygen saturation and little effect on forearm blood flow of the contralateral arm. Therefore, it is a better method for obtaining arterialized blood in forearm balance studies than the warming blanket.