What physiological effects occur under the cathode (negative pole) of an electrical stimulator?

What physiological effects occur under the cathode (negative pole) of an electrical stimulator?

• A. Vasodilation
• B. Vasoconstriction
• C. Irritation
• D. Edema reduction

Answer: (A)

Polarity of galvanic stimulation shapes local tissue responses, and the cathode (negative pole) tends to produce a vasodilatory effect in the underlying tissue. The direct electrical current at the cathode drives a chemical reaction that generates hydroxide ions, creating a local alkaline environment. This alkaline microenvironment can irritate superficial tissues and trigger vasodilatory mechanisms—including the release of local mediators and a reflex increase in blood flow—so more blood rushes to the area beneath the negative electrode. The mild heating from the current can further enhance this dilation. While irritation may occur due to the alkaline pH, and edema reduction is not the immediate polarity-driven change, the dominant immediate physiological response under the cathode is vasodilation.

Polarity of galvanic stimulation shapes local tissue responses, and the cathode (negative pole) tends to produce a vasodilatory effect in the underlying tissue. The direct electrical current at the cathode drives a chemical reaction that generates hydroxide ions, creating a local alkaline environment. This alkaline microenvironment can irritate superficial tissues and trigger vasodilatory mechanisms—including the release of local mediators and a reflex increase in blood flow—so more blood rushes to the area beneath the negative electrode. The mild heating from the current can further enhance this dilation. While irritation may occur due to the alkaline pH, and edema reduction is not the immediate polarity-driven change, the dominant immediate physiological response under the cathode is vasodilation.