Regulation of the cardiovascular function by CO2 laser stimulation in anesthetized rats

Physical stimulation of body surface points is known to affect various organ functions. In traditional Chinese medicine, so-called acupoints were defined. These points can be physically stimulated to effectively treat various diseases. Here we describe for the first time the effect of CO2 laser stimulation at the acupoints Neiguan (PC-6), Quchi (LI-11), Zusanli (ST-36), and Taichong (LR-3) on heart rate and mean arterial blood pressure in anesthetized rats. CO2 laser stimulation increased the skin surface temperature to 54A degrees C. Our results revealed that the laser stimulation at the left or right PC-6 and LR-3 increased heart rate and mean arterial pressure. There was no response of heart rate and mean arterial pressure during and after stimulation of the left LI-11, but laser stimulation at the right LI-11 slightly increased heart rate and mean arterial pressure. On the other hand, laser stimulation at the left and right ST-36 decreased heart rate and mean arterial pressure. The effects on mean arterial pressure were more pronounced than those on heart rate. After full spinal cord transection, all heart-rate and mean-arterial-pressure responses were attenuated or completely abolished. These results suggest that CO2 laser stimulation at either the left or right PC-6, ST-36, and LR-3, as well as at the right LI-11 can modulate the cardiovascular functions in anesthetized rats, and its modulatory site might be supraspinal.