Receptor crosstalk

There are at least three well‐defined signalling cascades engaged directly in the physiological regulation of cardiac circulatory function: the β1‐adrenoceptors that control the cardiac contractile apparatus, the renin‐angiotensin‐aldosterone system involved in regulating blood pressure and the natriuretic peptides contributing at least to the factors determining circulating volume. Apart from these pathways, other cardiac receptor systems, particularly the α1‐adrenoceptors, adenosine, endothelin and opioid receptors, whose physiological role may not be immediately evident, are also important with respect to regulating cardiovascular function especially in disease. These and the majority of other cardiovascular receptors identified to date belong to the guanine nucleotide binding (G) protein‐coupled receptor families that mediate signalling by coupling primarily to three G proteins, the stimulatory (Gs), inhibitory (Gi) and Gq/11 proteins to stimulate the adenylate cyclases and phospholipases, activating a small but diverse subset of effectors and ion channels. These receptor pathways are engaged in crosstalk utilizing second messengers and protein kinases as checkpoints and hubs f