A 6-year-old boy is brought to the family physician after his parents noticed that he had difficulty moving his arms and legs after a soccer game. About 10 minutes after leaving the field, the boy became so weak that he could not stand for about 30 minutes. Questioning revealed that he had complained of weakness after eating bananas, had frequent muscle spasms, and occasionally had myotonia, which was expressed as difficulty in releasing his grip or difficulty opening his eyes after squinting into the sun. After a thorough physical examination, the boy was diagnosed with hyperkalemic periodic paralysis. The family was advised to feed the boy carbohydrate-rich, low-potassiumfoods, give him glucose-containing drinks during attacks, and have him avoid strenuous exercise and fasting. What is the effect of hyperkalemia on cell membrane potential?