Sunday, 15 December 2013

The Effects of Hormone Catecholamines - Epinephrine(1)

Catecholamines, derived from the amino acid tyrosine, produced by the adrenal glands, which are found on top of the kidneys. are epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine. The hormone are released into the blood during times of physical or emotional stress.
A. Epinephrine
1. Epinephrine and thyroidism
In the study of measurement of the secretion rate of epinephrine in 6 euthyroid, 6 hyperthyroid, and 6 hypothyroid subjects infused at a constant rate for a one hour period with tritiated epinephrine (.01 muc/kg/min) (New England Nuclear Inc.), found that plasma secretion rates averaged 48 +/- 27 mug/kg/day in normal subjects, compared to 54 +/- 18 mu/kg/day in hyperthyroidism and 43 +/- 20 mug/kg/day in hypothyroidism. Likewise, the mean urinary secretion rate was 55 +/- 27 mug/kg/day in normal subjects compared to 60 +/- 22 mug/kg/day in hyperthyroidism and 50 +/- 28 mug/kg/day in hypothyroidism. There is no statistical difference between the values found in the three groups of subjects (plasma and urine). Therefore, these results would indicate that the signs and symptoms encountered in hyperthyroidism are not secondary to a high secretion rate of epinephrine(1).

2. Epinephrine-containing local anesthesia and cardiovascular disease
In the study to examine the safety of epinephrine-containing local anesthesia for use on patients with cardiovascular diseasein twenty-seven patients with cardiovascular disease, showed that Systolic blood pressure and heart rate increased by 4.1% and 5.1%, respectively, immediately after the lidocaine-epinephrine injection. Consequently, rate pressure product increased by 10.0%. Cardiac index increased by 14.2%, and total peripheral resistance decreased by approximately 10%. No patient complained of cardiac symptoms. There were no significant differences in hemodynamic responses related to the extent of the cardiac functional capacity(2).

3. Propranolol administration epinephrine-stimulated SSRBC adhesion in Sickle red blood cells (SSRBCs)  patients
Sickle red blood cells (SSRBCs) adhere to both endothelial cells (ECs) and the extracellular matrix. In the study to investigate whether systemically administered propranolol inhibits SSRBC adhesion and to document the safety of propranolol in SCD, indicated that Propranolol administration significantly reduced epinephrine-stimulated SSRBC adhesion in a dose dependent manner (p = 0.03), with maximum inhibition achieved at 40 mg. Adverse events were not severe, did not show dose dependence, and were likely unrelated to drug. No significant heart rate changes occurred. These results imply that β-blockers may have a role as antiadhesive therapy for SCD(3).

4. Hormone Epinephrine and sickle cell disease (SCD).
The possible role of physiologic stress hormones in enhancing adhesion of sickle erythrocytes (SS RBCs) to endothelial cells (ECs) in sickle cell disease (SCD). In the study of Epinephrine acts through erythroid signaling pathways to activate sickle cell adhesion to endothelium via LW-alphavbeta3 interactions, found that up-regulation of intracellular cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) by epinephrine significantly increased sickle but not normal erythrocyte adhesion to both primary and immortalized ECs. Inhibition of serine/threonine phosphatases also enhanced sickle erythrocyte adhesion at least partially through a PKA-dependent mechanism. Adhesion was mediated through LW (intercellular adhesion molecule-4 [ICAM-4], CD242) blood group glycoprotein, and immunoprecipitation studies showed that LW on sickle but not on normal erythrocytes undergoes increased PKA-dependent serine phosphorylation as a result of activation(4).

5. Low dose of intravenous (IV) epinephrine and monomorphic ventricular tachycardia (VT) in the setting of coronary artery disease
There is a report of three cases of sustained monomorphic ventricular tachycardia (VT) in the setting of coronary artery disease, resistant to beta-blockers in two patients and to amiodarone in all, successfully terminated by low doses of intravenous (IV) epinephrine. VT was the first manifestation of coronary artery disease in one patient, whereas the other two patients had a previous history of myocardial infarction and were recipients of an implantable cardioverter-defibrillator (ICD). One of these two patients experienced an arrhythmic storm. All had hemodynamic instability at the time of epinephrine administration(5).

6. Vitamin C and epinephrine
Vitamin C has several well-established roles in physiology including synthesis of collagen, carnitine and epinephrine, absorption of dietary iron, and mobilization of storage iron for erythropoeisis. Loss of several of these functions explains the pathology of scurvy, where defective collagen synthesis and anemia are major symptoms. Vitamin C deficiency is very common in dialysis patients and may arise from dialytic vitamin C clearance, restricted intake of vitamin C-rich foods, and increased vitamin C catabolism in vivo from inflammation. In the dialysis population, greater vitamin C intake may be needed for optimal health(6).

7. Epinephrine and cardiac arrest
Epinephrine is widely used in cardiopulmonary resuscitation for out-of-hospital cardiac arrest (OHCA). In the study to evaluate the association between epinephrine use before hospital arrival and short- and long-term mortality in patients with cardiac arrest, researchers at the Department of Health Services Management and Policy, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, showed that among patients with OHCA in Japan, use of prehospital epinephrine was significantly associated with increased chance of return of spontaneous circulation before hospital arrival but decreased chance of survival and good functional outcomes 1 month after the event(7).

8. Epinephrine in the treatment of anaphylaxis
In the study to review recent literature that impacts the use of epinephrine in the therapy of anaphylaxis, found that the intramuscular route of administration for epinephrine is superior has now been recognized by the guidelines, and because the site of choice has been found to be the lateral aspect of the thigh, the needle used for injection must be long enough to penetrate the vastus lateralis muscle and  outdated EpiPens can usually be administered safely, and alternative routes of administration, which may be more acceptable to patients, may be on the horizon as a result of preliminary studies assessing the administration of sublingual epinephrine by wafer(8).

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