Spasmolytic effect of cadmium and cadmium uptake in aorta

Abstract

1The relationship between inhibition of tension by Cd2+ in aorta and the kinetics of cadmium uptake and efflux was studied. Cd2+ (0.01-0.5 mM) inhibited the contraction of aorta to high-K+ (30 mM) in a dose-dependent manner.2 The high-K+-induced tension completely returned to control values after 60 min washing with a solution containing 5 mM disodium edetate (EDTA) or 5 mM cysteine, following a treatment with 0.5 mM Cd2+ for 30 min; after washing with normal medium only 15% of the control response returned. 3 Cadmium uptake increased with an increase of the Cd2+ concentration (0.0 1-0.5 mM). 4 Aortae preincubated with 0.5 mM Cd2+ for 60 min were washed subsequently with a medium containing 5 mM EDTA or 5 mM cysteine. About 5 % of the original tissue cadmium was retained after washing with EDTA or cysteine. 5 It is suggested that Cd2+ binds chiefly to the surface membrane of aorta. It seems possible that the quantity bound is correlated with the degree of inhibition of tension.

Regulation of 109Cd2+ Uptake into Isolated Neurohypophysial Peptidergic Nerve Terminals

“…In this series of experiments two compartments for Cd2+ accumulation have been distinguished on the basis of their sensitivity to the permeabilizing action of Triton X-100. Similar compartmentalization of cellular Cd2+ has been described in detail for everted intestinal sacs ( Hoadley and Johnson, 1987 ) , primary cultures of neonatal rat hepatocytes (Sorensen, 1988), and smooth muscle (Nasu, 1983;Ueda et al, 1988).…”

Metabolic Dependency of Cadmium Uptake and the Relaxant Effects of Cadmium in Smooth Muscle of Guinea Pig Tenia coli

“…The kinetics o f cadmium uptake and ef flux in tenia coli is more complex than that in aorta [Nasu, 1983]. Following treatment with 0.5 mmol/1 Cd2+ for short periods (1,5 min), the tension in tenia coli induced by high-K+ largely returned to normal upon washing with EDTA as compared with normal me dium.…”

“…Cadmium ions (Cd2+) have been shown to induce relaxation in ileal [Schnieden and Small, 1971; Osa, 1974;Nasu et al, 1983] and vascular [Thindct al" 1970; Toda, 1973;Nasu, 1983] smooth muscles. This relaxant activity in tenia coli has been believed to be effected at various sites o f action, and has been related to a decrease in Ca2+ uptake [Atow et al, 1983].…”

Manganese Ions Induce Tonic Contraction after Relaxation in a High-K+ Medium in Ileal Longitudinal Smooth Muscle of Guinea-pig

“…The contraction by Mn2+ in the high-K+ medium did not involve neural elements, since it was not affected by pretreatment with tetrodotoxin. After the application of other heavy metals such as Cd2+ (Nasu 1983;Nasu et a1 1983), Co2+ (Nasu 1992) or PbZ+ (Nasu et a1 1993) to the high-K+-induced contractions in ileal or aortic smooth muscles, the responses were also inhibited; however, the contractions did not develop entirely thereafter. Mn2+ itself at low concentrations (10-5-10-6 M) has been reported to cause a transient contractile response which ceased within several minutes (Schnieden & Weston 1969;Satoh et a1 1986).…”