Neurobiology concepts and research

Calcium Neuro

The Role of Calcium in Neurotransmission

Calcium channels and calcium ions, due largely to the significant positive charge of calcium ions (Ca++), have been demonstrated by empirical evidence that began mounting decades ago to be highly important in neurotransmission at the chemical synapses (Katz & Miledi, 1968; Dodge & Rahamimoff, 1967; Augustine & Charlton, 1986). At chemical synapses, changes in calcium ion concentration within and external to the terminal axon membrane create significant action potentials, and the concentration's degrees of variance demonstrate a non-linear impact on action potential that increases on an exponential scale (Katz & Miledi, 1968; Augustine & Charlton, 1986; Dodge & Rahamimoff, 1967). This paper will summarize and review three articles three article that discuss the importance of calcium ions in neurotransmission and especially in their presynaptic placement and functioning.

Katz and Miledi (1968) conducted a series of experiments using from neuromuscular structures and demonstrated quite clearly the role that calcium plays in the production of neural impulses and resultant muscular action. Through these experiments, Katz and Miledi (1968) showed that manipulating the intervals between neural impulses and thus altering the amount of time calcium ions were held in suspension to create depolarization had a significant impact on the degree of neural activation and ultimate muscular movement. For example, increasing the amount of time in which depolarization occurred by a simple factor of two, increased muscular movement fifty fold (Katz & Miledi, 1968). Their experiments demonstrated the high degree to which calcium facilitates and sets parameters for neural functioning (Katz & Miledi, 1968).

Slightly earlier research into the role of calcium in frog neuromuscular junction's function was able to describe with somewhat greater precision the mathematical relationship that appear s to exist between levels of calcium concentration and the degree of muscular movement observed (Dodge & Rahamimoff, 1967). It had been hypothesized that the release of four calcium ions is necessary for the release of one acetylcholine packet (which is necessary for the neuromuscular communication taking place at the neuromuscular junction), and thus that calcium has a cooperative impact on neuromuscular transmissions (Dodge & Rahamimoff, 1967). Specifically, these researchers noted a logarithmic scale that described the relationship between calcium ion concentration and the level of neuromuscular activity taking place during a given activation cycle that suggests the fourth power of calcium concentration is equal to action at the junction (Dodge & Rahamimoff, 1967).