Proadrenomedullin N-terminal 20 peptide (PAMP-[1-20]; ARLDVASEFRKKWNKWALSR-amide) is a potent hypotensive and catecholamine release-inhibitory peptide released from chromaffin cells. We studied the mechanism of PAMP action and how its function is linked to structure. We tested human PAMP-[1-20] on catecholamine secretion in PC12 pheochromocytoma cells and found it to be a potent, dose-dependent...

When clonal rat pheochromocytoma PC12h cells were cultured in a hormone-supplemented serum-free medium, the carbamylcholine-elicited catecholamine release from cells cultured in serum-free medium was completely abolished. On the other hand, the high potassium-induced catecholamine release was not changed, even in PC12h cells cultured in serum-free medium. The lack of carbamylcholine sensitivity...

1. We have reported a normal sodium (Na) pump, but decreased loop-diuretic-sensitive Na efflux in erythrocytes from patients with chronic renal failure on haemodialysis, suggesting a different mode of co-transport in uraemia. 2. The present work extends these findings and examines in vitro simultaneous unidirectional and radiolabelled Na and K fluxes through the Na/K/Cl co-transport and the Na/...

Determinants of 45Ca influx, 45Ca efflux, and 22Na efflux were examined in dog red blood cells. 45Ca influx is strongly influenced by the Na concentration on either side of the membrane, being stimulated by intracellular Na and inhibited by extracellular Na. A saturation curve is obtained when Ca influx is plotted as a function of medium Ca concentration. The maximum Ca influx is a function of ...

The aim of this study was to elucidate the effect of dietary variations of linoleic acid on the development of deoxycorticosterone acetate (DOCA)-salt hypertension in rats. All rats were divided into three groups and fed one of the following isocaloric diets with 8% NaCl: a high linoleic acid (HLA) (20% sunflower oil), a moderate linoleic acid (5% lard oil + 15% sunflower oil), or a low linolei...

Regulation of Na+ channels by neurotoxins has been studied in pinched-off nerve endings (synaptosomes) from rat brain. Activation of Na+ channels by the steroid batrachotoxin and by the alkaloid veratridine resulted in an increase in the rate of influx of 22Na into the synaptosomes. In the presence of 145 mM Na+, these agents also depolarized the synaptosomes, as indicated by increased fluoresc...

The mechanism by which ion-flux through the membrane-bound motor module (F0) induces rotational torque, driving the rotation of the gamma subunit, was probed with a Na+-translocating hybrid ATP synthase. The ATP-dependent occlusion of 1 (22)Na+ per ATP synthase persisted after modification of the c subunit ring with dicyclohexylcarbodiimide (DCCD), when 22Na+ was added first and ATP second, but...

Genistein, an isoflavone inhibitor of tyrosine-specific protein kinases, was shown to specifically block the 22Na+ influx through voltage-sensitive Na+ channels in cultured rat brain neurons, whereas other tyrosine kinase antagonists such as lavendustin A, compound 5, tyrphostin A47 and an erbstatin analog were inactive at concentrations known to block kinase activity in other neuronal systems....

PURPOSE To investigate the role of externally facing membrane protein sulfhydryl groups in controlling lens permeability and transparency using the impermeant sulfhydryl complexing agent p-chloromercuriphenyl sulfonate (pCMPS). METHODS Membrane permeability changes were studied by measuring lens voltage and resistance. Ion movements were monitored by measuring 22Na+ and 45Ca2+ fluxes, and int...

There are several meteoritic noble gas components whose isotopic abundances are distinctly different from the solar abundance. One of these components, Ne-E(L), is a 22Ne-rich component carried by presolar graphite. Neon-22 is dominantly from the radiogenic decay of 22Na (T1/2 = 2.6 a), but it also contains 22Ne produced by 14N(α, γ )18F(e+ν)18O(α, γ )22Ne. The proportions of 22Ne from the two ...