Atrial glands

Characterization of Amines from Individual Atrial Gland Vesicles of Aplysia califomica, Anal. Chem. 1998, 70, 3517. 

Lillard, S. J., Chiu, D.T., Scheller, R.H., Zare, R. N., Rodiiguez-Cruz, S. E., Williams, E. R., Orwar, O., Sandberg, M., and Lundqvist, J. A., Separation and characterization of amines from individual atrial gland vesicles of Aplysia califomica. Anal. Chem., 70, 3517-3524, 1998. 

Painter, S.D., Gustavson, A.R., Kalman, V.K., Nagle, G.T., and Blankenship, J.E. (1989) Induction of copulatory behavior in Aplysia atrial gland factors mimic the excitatory effects of freshly deposited egg cordons. Behav. Neural. Biol., 51, 222-236. 

The novel endocrine glands are the skin, gastrointestinal tract, adipose tissue, kidney (juxtaglomerular apparatus in the cortex which secretes renin that indirectly controls aldosterone secretion, via angiotensin-11), pineal gland, which secretes melatonin, and the heart (cardiac myocytes in the atria, which secrete atrial natriuretic peptide). 

The 5-HT4 receptors modulate the activities of channels and transporters by increasing cAMP levels. These include activation of L-type Ca2+ channels (326), chloride currents in human jejunal mucosa and rat distal colon (330,331), and the If pacemaker current in atrial myocytes (332) and stimulation of aldosterone release from the adrenal glands (333,334), striatal dopamine release (324), hippocampal and frontal cortex acetylcholine release (335,336), and hippocampal 5-HT release (337). 5-HT4 receptors also inhibit various channels, including a KV3.2-like delayed rectifier K+ channel (303), a voltage-activated K+ channel in colliculi neurons (320,338), a Ca2+-activated, afterhyperpolariz-ing, and K+ current in hippocampus (325). 

A significant study using extracts of rat cardiac atrial tissue produced copious excretion of urine, Na+ and Cl- at levels 30 times above normal on being injected into rats. The discovery of a saluretic peptide hormone thus established the heart as an endocrine gland with strong effects on water and electrolyte balance (Na+ and Cl-). Now named Atrial Natriuretic Factor (ANF), it may be useful in treating CHF patients in whom levels have been shown to be increased, yet are associated with decreased cardiac output. The normal effect of ANF infusion is to increase water, Na+, and K+ excretion and inhibit it for aldosterone and cortisone. Most of these effects do not occur in CHF patients, which may be the reason for the edema accompanying CHF. Why that is, however, remains to be seen. When the reasons become known, it may be possible to find a way around the CHF patient s inability to respond to ANF. That should solve many problems. 

Changes in water excretion that are secondary to altered intra-atrial pressure can be attributed largely to changes in the secretion of vasopressin by the posterior pituitary gland. This reflex has been documented both in experimental animals and in man, and the relevant data has been reviewed recently by Bie. on the other hand, it has not been possible, until recently, to account for the increased urinary Na+ excretion associated with changes in atrial pressure. 

The heart, as an endocrine organ itself, secretes the atrial natriuretic peptide, which has several important influences on the cardiovascular system. In addition to atrial natriuretic peptide, catecholamines, thyroid hormones, mineralocorticoids, sex steroids, and angiotensin II are other hormones also known to exert their effects on the cardiovascular functions and blood pressure. Hormones regulate the contraction and dilatation of the vascular bed. They may also affect the contraction of other smooth muscles other than the vascular smooth muscle. Oxytocin stimulates contraction of the myoepithelium in the mammary gland that is necessary for milk ejection. 

Schutz, H. 6c Gerstberger, R. (1990). Atrial natriuretic factor controls salt gland secretion in the pekin duck Anas ptatyrhyruhos) through interaction with high affinity receptors. Endrocrinology, 127, 1718-26. 

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