The influence of blood pressure on intracellular Ca2+ content in erythrocytes: effects of cadmium chloride and nifedipine

Impact of cadmium on liver pigmentary system of the frog Rana ridibunda

The liver pigmentary system of the frog Rana ridibunda was investigated after exposure to CdCl2. There was a time-dependent alteration in the area occupied by pigment cells. Most pigment was melanin, but lipofuscin and ferritin were also detected, being similarly increased with time. There was a time-dependent increase in the dimensions of pigment cells as a result of forming a cluster of more than two pigment cells, the so-called melanomacrophage aggregates (MMC). A thin capsule of connective tissue with fibroblast-like cells surrounds some MMCs. The various possible roles of MMCs are discussed, for instance, those of scavengers of foreign substances, for lowering of metabolic activities to survive in an anoxic environment probably caused by cadmium, or as scavenger of cadmium, thus playing a protective role against this metal.

The effects of short-term nifedipine treatment on responsiveness of aortic rings of cadmium-hypertensive rats

The effects of short-term antihypertensive treatment with nifedipine on blood pressure and vascular responsiveness were studied in cadmium-hypertensive and normotensive control rats. Cadmium administration caused a significant increase in mean arterial blood pressure. Endothelin-1, noradrenaline and angiotensin II produced concentration dependent contractions of aortic rings that attained a lower maximal contraction in cadmium-hypertensive rats. Responses of aortic rings to KCl did not show a significant difference between the groups. Nifedipine administered simultaneously with cadmium inhibited the induction of hypertension. Nifedipine treatment for 5 days significantly reduced the blood pressure in cadmium-hypertensive and normotensive rats. Neither inhibition of hypertension nor normalization of blood pressure in cadmium-hypertensive rats caused an alteration in contractile responses of aortic rings to vasoconstrictors which suggested that development of decreased vascular reactivity and of hypertension occurs simultaneously in cadmium-hypertensive rats but the role of decreased vascular reactivity in maintenance of hypertension is questionable in cadmium-hypertension.