Figure 1.

This cartoon illustrates mechanisms that are linked to ET receptor-dependent increases in [Ca²⁺]_i. In addition to the plasma membrane receptors, ET_B receptors in the nuclear membrane may mobilize calcium when activated by cytosolic ET-1. While the ET_A receptor is shown only in the plasma membrane, ET_B receptors are found in both the plasma and nuclear membranes. It is unknown if ET_A receptors are in the membrane of other organelles. Many of the same mechanisms are attributed to both ET_A- and ET_B-dependent increases in [Ca²⁺]_i. Arrows represent activation; teed lines represent inhibition. Abbreviations: AC, adenylate cyclase; ADPRC, ADP-ribosyl cyclase; cADPR, cyclic ADP ribose; cAMP, cyclic adenosine monophosphate; CHX, calcium/hydrogen antiporter; CICR, calcium-induced calcium release; DAG, diacylglycerol; ECF, extracellular fluid; ET-1, endothelin-1; IP₃, inositol trisphosphate; IP₃R, inositol trisphosphate receptor; MITO, mitochondria; NAADP, nicotinic acid adenine dinucleotide phosphate; NAD⁺, nicotinamide adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate; NCX, sodium/calcium exchanger; NSCC, non-selective cation channel; NUC, nucleus; PKA, protein kinase A; PKCα, protein kinase C-α; PLC-β, phospholipase C-β; RyR, ryanodine receptor; SER, smooth endoplasmic reticulum; SOCC, store-operated calcium channel; VGCC, voltage-gated calcium channel.