THE RELATION OF SERUM BICARBONATE CONCENTRATION TO MUSCLE COMPOSITION

NaHCO3 loading causes increased arterial pressure and kidney damage in rats with chronic kidney disease

Sodium bicarbonate (NaHCO3) is commonly utilized as a therapeutic to treat metabolic acidosis in people with chronic kidney disease (CKD). While increased dietary sodium chloride (NaCl) is known to promote volume retention and increase blood pressure, the effects of NaHCO3 loading on blood pressure and volume retention in CKD remain unclear. In the present study, we compared the effects of NaCl and NaHCO3 loading on volume retention, blood pressure, and kidney injury in both 2/3 and 5/6 nephrectomy remnant kidney rats, a well-established rodent model of CKD. We tested the hypothesis that NaCl loading promotes greater volume retention and increases in blood pressure than equimolar NaHCO3. Blood pressure was measured 24 h daily using radio telemetry. NaCl and NaHCO3 were administered in drinking water ad libitum or infused via indwelling catheters. Rats were housed in metabolic cages to determine volume retention. Our data indicate that both NaHCO3 and NaCl promote hypertension and volume retention in remnant kidney rats, with salt-sensitivity increasing with greater renal mass reduction. Importantly, while NaHCO3 intake was less pro-hypertensive than equimolar NaCl intake, NaHCO3 was not benign. NaHCO3 loading significantly elevated blood pressure and promoted volume retention in rats with CKD when compared with control rats receiving tap water. Our findings provide important insight into the effects of sodium loading with NaHCO3 in CKD and indicate that NaHCO3 loading in patients with CKD is unlikely to be benign.

The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO3˙− as the active intermediate

The reaction Co(H₂O)₆²⁺ + H₂O₂ proceeds via a transient that decomposes into Co^II(H₂O)(OOH)(OH)₂ + CO₃˙⁻. Plausible biological implications are pointed out.

Salt, the kidneys, and arterial hypertension

The kidneys play a major role in the regulation of the salt balance and thereby regulate blood pressure. Salt sensitivity is acquired or genetically-induced and is noted in about 50% of patients with essential hypertension. This property leads to a high cardiovascular risk. In this situation, the benefit of salt restriction is significant, and this dietary change should be associated with a high potassium intake. In patients treated by antihypertensive drugs, salt restriction improves the blood pressure control, which can permit a reduction of the number of drugs required to achieve a normal blood pressure. The recommended maximal salt intake should not exceed 6 grams/day (NaCl). Because most dietary salt comes from processed foods, the help of the food industry is crucial for a long-term compliance with a reduced salt intake, which could yield an additional important benefit in the reduction of cardiovascular risk.

Importance of dietary chloride for salt sensitivity of blood pressure

Recent evidence indicates that the anion accompanying sodium plays an important role in determining the magnitude of the blood pressure increase in response to a high dietary intake of NaCl. The purpose of this review is to describe studies of blood pressure responses to selective dietary sodium loading (without chloride) and to selective dietary chloride loading (without sodium) in several experimental models of salt-sensitive hypertension and in hypertensive humans. The full expression of salt sensitivity depends on high dietary intakes of both sodium and chloride. This observation has implications for understanding mechanisms contributing to NaCl-induced hypertension.

Relationship of hypokalemia to metabolic alkalosis in the intact Yucatan miniature boar following implantation of deoxycorticosterone-acetate (DOCA) or d-aldosterone

1. Normo-kalemic Yucatan miniature boars were implanted with deoxycorticosterone-acetate (DOCA) or d-aldosterone (Aldo) to evaluate the relationship of hypokalemia to the pathogenesis of metabolic alkalosis following mineralocorticoid administration. 2. Serum potassium was significantly less than control within 24 hr, serum bicarbonate significantly elevated within 4 days and pH 1-2 days later with no significant differences between DOCA and Aldo. 3. These data demonstrate that pre-existing potassium deficits are not required for the development of alkalosis with mineralocorticoid administration, DOCA and Aldo are equally effective, co-existing hypokalemia is necessary in the genesis, and perhaps maintenance, of metabolic alkalosis with excess mineralocorticoids, and hypokalemia is not a consequence of the alkalosis.

Relative contributions of dietary Na+ and Cl- to salt-sensitive hypertension

The effect of dietary NaCl on blood pressure has generally been attributed to the sodium ion. However, recent evidence indicates that the anion accompanying sodium plays an important role in determining the magnitude of the blood pressure increase in response to a high dietary intake of NaCl. The purpose of this review is to describe studies of blood pressure responses in several experimental models of salt-sensitive hypertension and in hypertensive humans to selective dietary sodium loading (without chloride) and to selective dietary chloride loading (without sodium). The full expression of salt sensitivity depends on high dietary intakes of both sodium and chloride. This observation has implications for understanding mechanisms contributing to NaCl-induced hypertension in the susceptible host.

Tetany induced by hypokalemia in the absence of alkalosis

A 36-year-old patient developed tetany manifested only by a positive Trousseau's sign and with a negative Chvostek's sign 8 weeks after gastric bypass surgery for obesity. The usual causes of tetany (hypocalcemia, hypomagnesemia and alkalosis) were absent. The only possible etiology found was hypokalemia. Previous cases of hypokalemia induced tetany reported were always accompanied by alkalosis. Its absence in our patient makes this case unique and determines that hypokalemia per se in the absence of alkalosis may be a cause of tetany. It is suggested that the Trousseau's sign should be investigated in patients with severe potassium deficiency.

Metabolic alkalosis in the Yucatan miniature boar following desoxycorticosterone-acetate (DOCA) implantation

Metabolic alkalosis was induced in adult Yucatan miniature boars by subcutaneous implantation of desoxycorticosterone-acetate impregnated silicone rubber strips. Serum pH, bicarbonate, and PaCO2 increased rapidly and consistently following implantation. As in the dog and the rat, hypokalemia was accompanied by hypochloremia. As in the rabbit, hypokalemia developed in the presence of a decreased urinary output of potassium and apparent absence of kaliuresis. The pig is resistant to the paralytic effects of hypokalemia. Implantation of DOCA is an effective means of producing chronic metabolic alkalosis in the pig which is characterized by hypokalemia and hypochloremia.

Changes in cellular and subcellular composition during potassium deficiency

1. A specific dietary deficiency of potassium in young rats reduced the potassium concentration in thigh muscle by 48%, and in heart and kidney by 18%, but did not significantly affect the concentration in liver or brain. Conversely the sodium concentration rose in liver, heart and thigh muscle, and thigh muscle also accumulated increased amounts of magnesium. Apart from an increase in the water content of many tissues, no consistent changes in the composition of major cell constituents were observed. 2. The loss of potassium and accumulation of sodium and magnesium occurred predominantly in the supernatant fraction of the cell. The supernatant of all tissues studied contained about 80% of the total cellular potassium and sodium, and the potassium was present entirely in the ionic form. 3. Potassium and magnesium are the two most abundant intracellular metals, but their deficiencies have very different effects on the cell. The relationship between them is more complex than the inverse relationship between potassium and sodium.

Electrolyte metabolism of muscle in the salt-losing form of congenital adrenal hyperplasia

The study of metabolism of muscle electrolyte in children with the salt-losing form of congenital adrenal hyperplasia reveals two types of alterations. After admission and during initial therapy with salt and desoxycorticosterone, the changes are typical of those seen in experimental animals with adrenalectomy and excessive replacement therapy. Discontinuation of the sodium supplement after three months of therapy resulted in a return of muscle electrolyte values to normal. During the period of poor growth common to these patients a different pattern was observed. Sodium and water accumulated without alteration in tissue potassium. The mechanism of this alteration is not clear; however, it is consistent with the known effects of excess cortisone on muscle composition. These observations permit the conclusion that at least two fractions of sodium are present in muscle fibers, that which exchanges potassium and that which is independent of potassium metabolism.