Delivered April 27th, 2020. Contributors: Hanine K.
Alkali Metals: Biological Effects
Alkali metals make up Group 1 of the periodic table. These metals are "lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr)." Sodium and Potassium are the most abundant alkali metals, while rubidium, lithium, and cesium are rare, and francium is very rare.
Alkali metals "react with moisture to generate caustic products (hydroxides)." These products may cause skin chemical burns (due to the action of hydroxides) and skin thermal burns (due to the heat of the reaction).
Lithium cations are used for "the prevention and treatment of neurodegenerative diseases and different psychiatric disorders such as bipolar disorder, unipolar depression, schizophrenia, and mania because it acts on the regulation of neurotransmitters and mitochondrial function, attenuating the expression of genes associated with the signaling pathways of protein kinases A and C (PKA/PKC) in hyperexcitable neurons, favoring the stability of mood."
The mechanism of action of the first alkali metal, lithium, is still unknown. Two hypotheses explain its mechanism: Lithium stabilizes neural membranes or modifies neural second messenger systems.
Sodium Na: Regulation of Osmotic Pressure and Blood Pressure
Sodium ions regulate neuron function, blood volume, blood pressure, and osmotic pressure. Sodium with higher-level PH prevents "kidney failure, loss of fluids, hypothyroidism, heart failure, and liver cirrhosis."
To maintain and regulate blood and osmotic pressure, sodium works mainly on regulating muscle movements (contractions and relaxations), maintaining water balance, and transmitting nerve messages and impulses (along with potassium ions).
Sodium hydroxide "can irritate the eyes, skin, and nose, but in more extreme amounts may cause chemical bronchitis."
Potassium K: Osmotic Balance
Potassium plays a major role in maintaining the "osmotic balance between cells and interstitial fluid and in maintaining the fluid and electrolyte balance."
However, higher concentrations of potassium in the human body lead to the formation of excessive fluid in the lungs, causing death.
Rubidium: Biological Effects
Rubidium (Rb) is an alkali metal element, naturally present as Rb and radioactive Rb, accounting for 72.15% and 27.85% of the rubidium on Earth, respectively. The alkali metal is found "in trace amounts in the rock-forming silicate minerals, such as potassium feldspars and micas."
Known for being water-soluble, rubidium compounds, such as rubidium hydroxide, rubidium iodide, and rubidium chloride, are used for therapeutic applications. An example is rubidium chloride, which is an antidepressant. Another example is rubidium iodide, which treats goiter.
The alkali metal enhances the turnover of brain norepinephrine, by activating electroencephalogram. While there is no evidence on how rubidium activates electroencephalogram in humans, it is verified that "rubidium causes electroencephalogram activation in monkeys and rats, perhaps the depletion of rubidium prevents the normalization of low-wave power values in dialysis patients."
Toxicology of Rubidium: Overexposure
Rubidium records show very low toxicity levels, because the "ingested rubidium is almost completely absorbed into portal blood, carried temporarily by erythrocytes." These low levels are also due to the fact that the alkali metal could not be accumulated in any way in human organs or tissues.
To measure the toxicology of rubidium, the most important method is the ratio of rubidium to potassium (Rb/K) intake. A ratio above 40% is considered as a dangerous ratio.
In the case of overexposure, rubidium may cause eye and skin burns. Other symptoms of overexposure include, but not limited to, ataxia, skin ulcers, and failure to gain weight. Additionally, "human occupational exposures to high levels of rubidium have produced headaches, lassitude, irritability, disturbed sleep, cardiac arrhythmia, peripheral neuropathy, inflammation of the respiratory tract, and kidney damage with proteinuria."
As a source of iodine, rubidium iodide is used in the treatment of goiter. A variety of anecdotal reports and case studies suggest that rubidium promotes thyroid metabolism. The mechanism of this effect is unknown.