Endogenous cardiac opioids: Enkephalins in adaptation and protection of the heart

Cellular localization and adaptive changes of the cardiac delta opioid receptor system in an experimental model of heart failure in rats

“…Activation of such neuronal ORs induces pertussis-toxin sensitive G protein coupling (G i and/or G o ), adenylyl cyclase inhibition, decreased intracellular cAMP, and inhibition of voltage-gated calcium channels which among other downstream processes contribute to contribute to the inhibition of pain [2]. However, there is a growing body of data supporting a local role of opioids in the regulation of organ systems such as the gut [3], lung [4], and heart [5,6].…”

Effect of opium use on short-term outcome in patients undergoing coronary artery bypass surgery

“…Some investigations have shown that opioid peptides, particularly enkephalins, play an important role in a number of physiological and pathological conditions in the heart such as ischemic preconditioning via the K + -ATP channel in cardiac mitochondria. 7,8 The exact action of opium is not clear, however; and there is controversy, even among medical staff, about the effects of opium on the cardiovascular system. Furthermore, no data are available regarding the effect of opium on the short-term outcome in patients undergoing coronary artery bypass grafting (CABG).…”

“…6 Endogenous ligands for the opiate receptors have been identifi ed and termed opioid peptides. 7 These ligands are presented in the heart, interact with opioid peptide receptors, and play an important role in cardiovascular responses, including hypotension, bradycardia, peripheral vasodilatation, and sometimes hypertension and tachycardia. Some investigations have shown that opioid peptides, particularly enkephalins, play an important role in a number of physiological and pathological conditions in the heart such as ischemic preconditioning via the K + -ATP channel in cardiac mitochondria.…”

Prognostic value of neuropeptide proenkephalin A in patients with severe traumatic brain injury

“…Enkephalins are also found at high levels in the brain and endocrine tissues [4,8,9], and even in non-neuronal tissues [6]. Studies have shown that enkephalins play an important role in behavior, pain, cardiac function, cellular growth, immunity and ischemic tolerance [2,14,15,35]. Enkephalin levels in the peripheral blood are associated with severity and prognosis of some illness such as liver disease, human hepatic encephalopathy, and primary biliary cirrhosis [17,[32][33][34].…”