Increased vascular response to adrenergic stimulation in rats exposed to cadmium

Publisher Website
Google Scholar
Abstract
Adult female rats were injected ip with a low total dose (1–2.25 mg/kg) or a high total dose (7.5 mg/kg) of cadmium, as cadmium chloride with cysteine, given in divided doses spaced over 1–3 wk. At 1–4 wk after administration of high doses of cadmium, anesthetized rats were less responsive to the pressor effect of norepinephrine (1.0–10.0 μg/kg, iv) than were controls. This type of effect has been described previously by other investigators and was not explored further in this study. In contrast to the results in high‐cadmium animals, anesthetized rats of the low‐cadmium group, tested 1–4 wk after exposure, were more sensitive to the pressor effects of norepinephrine (0.1–10.0 μg/kg, iv) than were controls. This increase in sensitivity was no longer apparent in animals tested 16–26 wk later. Neither basal blood pressure in anesthetized animals nor systolic pressure in conscious animals of the low‐cadmium series was different from the corresponding value in controls. Aortic rings isolated from low‐cadmium animals 1–4 wk after cadmium exposure developed more tension in the presence of norepinephrine (10−9 –10 −7 M) than did similar preparations obtained from control rats. Tail arteries isolated from low‐cadmium animals 1–4 wk after exposure exhibited a greater pressor response to periarterial sympathetic nerve stimulation than did arteries from control rats. It is concluded that cadmium can affect the vascular response to norepinephrine without altering basal blood pressure, and that the direction of the effect is dependent on the level of exposure.