Abstract
This review covers the role of the sarco(endo)plasmic reticulum in regulating Ca influx across the plasma membrane, the role of cytosolic free Ca in modulating mitochondrial function, and the role of the plasma membrane in regulating sarco(endo)plasmic reticulum Ca, focusing on recent findings that shed a new light on cellular Ca regulation. Mechanisms of interactions among the sarco(endo)plasmic reticulum, mitochondria, and the plasma membrane are discussed with a view to explain the lack of consensus regarding the relationship between the cytosolic free Ca and blood pressure, and the enigmatic behavior of the Na-H exchanger in blood cells (primarily platelets and lymphocytes) from patients with essential hypertension.