Electron probe x-ray microanalysis of the composition of rabbit portal anterior mesenteric vein smooth muscle was performed following sodium loading and washout into sodium-free lithium solutions. Sodium and lithium were also measured with atomic absorption spectrophotometry. Cellular uptake of sodium and loss of potassium during sodium loading were much faster at high (37 degrees C) than at lo...

The membrane potential in the dark and the saturated response height of the ventral nerve photoreceptor of Limulus was measured by an intracellular electrode while the external concentra­ tion of calcium, magnesium and sodium ions was varied. Decreasing the extracellular calcium concentration from 10-2 mol/1 causes a calcium-dependent lowering of the dark membrane potential and at very low conc...

After chronic spinal injury, motoneurons spontaneously develop two persistent inward currents (PICs): a TTX-sensitive persistent sodium current (sodium PIC) and a nimodipine-sensitive persistent calcium current (calcium PIC). In the present paper, we examined how these PICs contributed to motoneuron firing. Adult rats were spinalized at the S(2) sacral level, and after 2 months intracellular re...

In a balanced diet, roughly 1000 mg of calcium is ingested each day and about 200 mg is secreted in the bile and other gastrointestinal secretions. Depending on the comcentrations of circulating parathyroid hormone (PTH) and active i.25.di-(OH)D3 about 200-400 mg is absorbed from the intestine each day. The remaining calcium is excreted in the stool. Maintenance of body calcium stores depends o...

Acidosis in cardiac myocytes is a major factor in the reduced inotropy that occurs in the ischemic heart. During acidosis, diastolic calcium concentration and the amplitude of the calcium transient increase, while the strength of contraction decreases. This has been attributed to the inhibition by protons of calcium uptake and release by the sarcoplasmic reticulum, to a rise of intracellular so...

The contributions of electrogenic sodium/calcium exchange current ( I NaCa), calcium-activated chloride conductance [ I Cl(Ca)], and calcium-activated nonselective cation conductance to delayed afterdepolarizations (DAD) were examined. Nonselective cation channels were absent in canine M cells, since inhibition of I NaCa and I Cl(Ca)eliminated all calcium-activated currents without abolishing c...

Exchange-inhibitory peptide (XIP) can inhibit sodium-calcium exchange without inhibiting L-type calcium current (ICa). We therefore used this compound to test the hypothesis that reverse sodium-calcium exchange can trigger contraction in guinea pig ventricular myocytes. When cells were dialyzed with 20 mmol/L sodium, rapid blockade of ICa with nifedipine had little effect on cell shortening. Ho...

Rat brain microsomes, immobilized on a filter, were perfused with ATP-containing solutions in a device which made possible rapid change of perfusion media and frequent sampling of effluent. Inorganic phosphate production could be measured 10 times per sec. When ATP, sodium, or potassium was absent from the first perfusion medium and present in a second, and introduced without interrupting flow,...

Renin is the critical regulatory enzyme for production of angiotensin (Ang)-II, a potent vasoconstrictor involved in regulating blood pressure and in the pathogenesis of hypertension. Chronic sodium deprivation enhances renin secretion from the kidney, due to recruitment of additional cells from the afferent renal microvasculature to become renin-producing rather than just increasing release fr...

introduction this study was intended to evaluate the nutritional value, phenolic compounds and digestibility coefficients of barberry leaves. berberis vulgaris is one of the major crops in the province. the province has more than 70 percent and 95 percent of the total area under cultivation of barberry. waste and foliage of barberry harvest traditionally used to feed livestock tannin concentrat...