Effects Of Formaldehyde On Rat Aortic Ring Tension

Environmental pollution has been increasing since the industrial revolution, and now people are paying more and more attention to the harm of various kinds of environmental pollutants. Formaldehyde as a typical representative of indoor pollutants, it can not only enter the body from outside air and be an endogenous substance. In recent years, a large number of epidemiological studies have shown that formaldehyde has toxicity in nervous system, immune system, reproductive system, respiratory system and cardiovascular system. And the reports have shown that formaldehyde may cause some cardiovascular diseases such as vascular endothelial or myocardial tissue injury, aortic rings relaxation, atherosclerosis and myocardial infarction. It is important to study the toxicity and mechanism of formaldehyde on cardiovascular function for the development of its toxic mechanism and cardiovascular disease, but so far, effects of formaldehyde on the cardiovascular system and the mechanism have not been reported in detail. So, we study the effect of formaldehyde on rat aortic ring tension and the specific mechanism.1. This study was designed to observe the effect of formaldehyde on the aortic ring tension in vitro, we found that:Formaldehyde at low concentration (<300μM) had certain contraction effect on aortic rings, formaldehyde at high concentration(>500μM) had relaxation effect on aortic rings, and showed dose dependent relationship, only when the formaldehyde concentration was greater than 3 mM, relaxation effect no longer increases. Formaldehyde at low concentration had contraction effect on endothelium-intact and endothelium-denuded aortic rings, formaldehyde at high concentration had relaxation effect on endothelium-intact and endothelium-denuded aortic rings, and the difference was significant, so effect of formaldehyde on aortic rings tension was related with endothelium. Formaldehyde at low concentration had not significant relaxation function on vascular rings were contracted by 100 mM KCl, but it had significant relaxation function on vascular rings were contracted by 20 mM KCl; formaldehyde at high concentration had obvious relaxation function on vascular rings were contracted by 100 mM KCl, but it could promote the contraction effect induced by 20 mM KCl. The results showed that formaldehyde could impact rat aortic rings tension, formaldehyde at low concentration had minor contraction effect on vascular rings, formaldehyde at high concentration had relaxation effect on vascular rings and showed dose dependent relationship, the vasodilatation effect induced by formaldehyde might be related to potassium ion channel conductance.2. L-Ca2+ channel blocker nifedipine, Large conductance calcium activated potassium channel blocker IbTx, non specific potassium channel blocker TEA, nitric oxide synthase inhibitor L-NAME, guanylate cyclase inhibitor NS-2028 had some inhibitory effect on vasodilatation induced by formaldehyde at high concentration. The results showed that the mechanism of vasodilatation induced by formaldehyde might be related to L-Ca2+ channel, BKca channel and NO-cGMP pathway.3. With the method of cumulative addition of norepinephrine(NE), calcium chloride (CaCl2), potassium chloride (KCl) made the vascular rings contract, we found that formaldehyde at high concentration could inhibit vasoconstriction effect induced by NE, CaCl2 and KCl. The results showed that formaldehyde at high concentration had inhibitory effect on voltage dependent calcium channel (VDC) and receptor operated calcium channel (ROC).The study showed that formaldehyde at low concentration can make aortic rings contraction, but formaldehyde at high concentration can make aortic rings relaxation, the mechanism may be related with the different ion channels.