The effects of chronic AC magnetic field on contraction and relaxation of isolated thoracic aorta rings of healthy and diabetic rats

摘要

Our aim in this study was to determine the effect of chronic alternating current (AC) magnetic field on the contraction and relaxation parameters of isolated thoracic aorta rings in healthy and diabetic rats. Forty rats (Wistar albino spp) weighing between 250-300 g were used. The rats were first divided into four groups. The first group was made up of the control rats (C, n=10), the second group was comprised of rats described as control+magnetic field group (C+MA, n=10), third group contained experimental diabetic rats (DIA, n=10), and the fourth group was comprised of both experimental diabetic and magnetic field group (DIA+MA, n=10). Magnetic fields of 5 mT intensity and 50 Hz frequency oriented in the north-south direction was applied to the C+MA and DIA+MA groups for 2 hours each day for one month. The rats were weighed once every week during the one-month period. The measurements were expressed in grams. After the one-month study period, rats were killed by decapitation and the thoracic aorta dissected, and excess fats or connective tissues removed. Each ring was prepared with length 3-4 mm. Two stainless steel hooks were inserted into the lumen of the isolated blood vessel; one was fixed and the other connected to a force-displacement transducer (GrassFT03). Rings were prepared under a resting tension of 2 g after 2 hours in Krebs solution. The organ bath medium was maintained at 37/spl plusmn/0.1/spl deg/C and aerated with 95% O/sub 2/+5% CO/sub 2/ previously. Isometric tension measurements were recorded with the model 7 polygraph. We used phenylephrine for contraction responses and acetylcholine or sodium nitropruside for relaxation responses. The contractions were calculated in grams, and the relaxations expressed as percentage peak reduction of phenylephrine contracture. We observed attenuated contraction responses to PE and elevated relaxation responses to ACh of the thoracic aorta rings of rats in the C+MA and DIA+MA groups compared to group C but no changes in the relaxation responses to sodium nitroprusside of thoracic aorta rings relative to group C and DIA. The weights of rats in DIA+MA or C+MA groups compared to the DIA and C groups were decreased.