Angiotensin II is a potent vaso-active peptide that causes blood vessels to constrict, resulting in increased blood pressure. Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the tubules of the kidneys to increase the reabsorption of sodium and water into the blood.
The most reliable record of a Blue Shark at speed is 24.5 miles (39.4 kilometres) per hour for a 6.5-foot- (2-metre-) long individual. The Shortfin Mako (Isurus oxyrinchus) is probably the champion speedster among sharks.
There exists a dubious record of a small Blue Shark about two feet in length which was found to swim steadily against a current at 17.7 mph and was reported to achieve 43 mph in short bursts. The most reliable record of a Blue Shark at speed is 24.5 mph for a 6.5-foot-long individual.