THE EFFECT OF 3 PRODUCTS OF CIGARETTE-SMOKE (CYANIDE, THIOCYANATE ANDNICOTINE) ON THE CONCENTRATION-RESPONSE CURVES OF 5-HYDROXYTRYPTAMINE, NOREPINEPHRINE AND EPINEPHRINE IN THE ISOLATED HUMAN UMBILICAL VEINSAND ARTERIES

The effect of cyanide (10(-7) M), thiocyanate (10(-4) M) and nicotine (10(-7) M) on the concentration-response curves of 5-hydroxytryptamine , norepinephrine and epinephrine were investigated in human isolated u mbilical arteries and veins. Cyanide significantly affected the respon ses of arterial strips to 5-hydroxytryptamine, norepinephrine and epin ephrine: It caused significant leftward shifts of the 5-hydroxytryptam ine concentration-response curves and significantly potentiated the co ntractile effects of norepinephrine and epinephrine in the case of nor epinephrine, and epinephrine concentration reached 10(-6) and 10(-7) M respectively in the bath medium. Cyanide did not show any significant effect on the concentration-response curves of 5-hydroxytryptamine, n orepinephrine and epinephrine in veins. Nicotine interacted with the r esponse of adrenergic agonists both in arteries and veins; in arteries it potentiates the contractile response of epinephrine; in veins, it inhibited the dilatory responses of norepinephrine and potentiated the contractile effect of high concentration of epinephrine (10(-6) M). T hiocyanate did not cause any difference on any cumulative concentratio n-response curves either on the vessels. However, none of these indivi dual effects of cyanide and nicotine were observed when the cyanide, t hiocyanate and nicotine were added in combination in the isolated orga n bath medium.