Epinephrine blood glucose effects

Figure 2S-I0 Hormonal regulation of blood glucose. Key +, stimulation —, inhibition. Cortisol, growth hormone, and epinephrine also antagonize the effect of insulin.

The increase in cAMP is a hormonal message which has an effect in two major target organs, liver and muscle, but different hormones affect increased cAMP in each. In the liver, the hormone is glucagon, whereas in the muscle, the hormone is epinephrine. In the liver, glycogen breakdown (i.e., glycogenolysis) can serve as a source of hexose phosphate, a precursor of blood glucose in the... 

Epinephrine and norepinephrine are catecholamines which, when released from presynaptic nerve endings, function as neurotransmitters (see here). When released from adrenal medulla in response to low blood glucose levels, epinephrine interacts with second-messenger systems in many tissues, with varied effects. In muscle, epinephrine activates adenylate cyclase, with concomitant activation of glycogenolysis and inhibition of glycogen synthesis. 

Epinephrine also inhibits insulin secretion and stimulates glucagon secretion. These effects tend to increase glucose production and release by the liver. The net result is to increase blood glucose levels. 

The most important hormone promoting glucose uptake and use is insulin, whereas both glucagon and epinephrine act conversely, to increase blood glucose levels. The major effects of these agents are summarized in Table 23.2. 

Describe the effects of beta agonists, such as epinephrine and ephedrine, on blood glucose. 

Hormones have several important functions in the body. They help maintain homeostasis, the balance of biological activities in the body. The effect of insulin in keeping the blood glucose level within narrow limits is an example of this function. The operation of epinephrine and norepinephrine in the fight-or-flight response is an example of the way in which hormones mediate responses to external stimuli. Finally, hormones play roles in growth and... 

The exact cause of reactive hypoglycemia is difficult to determine, but most researchers believe that the main cause is a shortage of glucagon, resulting in an inability to raise blood glucose levels when necessary. Others speculate that the cause is a hypersensitive response to the release of the normal physiological hormone called epinephrine, a reaction that is the opposite of epinephrine s normal effect on blood sugar, which is to raise it. Still others consider excessive insulin production to be the culprit. 

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