Fig. 2

Renin-angiotensin system. ACE2 is exploited by SARS-CoV-2 when infecting host cells. Renin, secreted from the kidneys in response to changes in blood flow and pressure, catalyses the conversion of the plasma protein called angiotensinogen into angiotensin I, angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II. Angiotensin II acts via receptors in the adrenal gland, causing the secretion of aldosterone, which causes the kidney to reabsorb salt and water. Angiotensin II is a powerful vasoconstrictor. ACE2 activity alters the ratio between angiotensin I to angiotensin (1–9) and angiotensin II to angiotensin (1–7). Angiotensin (1–7) can be converted to angiotensin (1–9) by ACE, and both have been shown to cause vasodilation. It has been shown that SARS-CoV-2 spike protein binds to the ACE2 receptor and shift the balance towards angiotensin II