¼±Åà - È­»ìǥŰ/¿£ÅÍŰ ´Ý±â - ESC

 

Neurohypophysis

hypothalamusÀÇ supraoptic nucleus & paraventricular nucleusÀÇ large cell body¿¡¼­ »¸¾î

³ª¿À´Â axonÀ¸·Î Çü¼ºµÇ¸ç µÎ°¡Áö È£¸£¸óÀ» »ý¼ºÇÑ´Ù.

i) arginine vasopressin(AVP) = ADH

ii) oxytocin

AVP´Â renal tubule¿¡ ÀÛ¿ëÇÏ¿© water retention, urine concentrationÀ» ÀÏÀ¸Å°°í

oxytocinÀº suckling½Ã postpartum milk letdownÀ» ÀÚ±ØÇÑ´Ù.

AVP deficiency´Â DI¸¦ ÀÏÀ¸Å°°í AVP excess or inappropriate productionÀº hyponatremia,

water retentionÀ» ÀÏÀ¸Å²´Ù.

oxytocin deficiency or excess¿Í °ü·ÃÇÑ clinical disorder´Â ¾Ë·ÁÁø °ÍÀÌ ¾ø´Ù.

Vasopressin

1) ÀÛ¿ë Fig 329-2

collecting tubule cell surfaceÀÇ G protein-coupled V2 receptor¿¡ °áÇÕÇÏ¿©

adenylate cyclase¸¦ activation(cAMP¡è)½ÃŲ´Ù.

±× °á°ú aquaporin 2¶ó´Â ´Ü¹éÁú·Î ÀÌ·ç¾îÁø water channelÀÌ apical membraneÀ¸·Î

À̵¿ÇÏ°Ô µÈ´Ù.

cf. aquaporin 2 water channel : apical membrane

aquaporin 3, 4 : basal-lateral surface

tight junction: unregulated water flow¹æÁö

°í³óµµÀÇ AVP´Â ¸î°¡Áö ´Ù¸¥ ÀÛ¿ëµµ ÀÖ´Ù.

i) skin, GI blood vesselÀÇ smooth muscle contraction

ii) liver glyogenolysis

iii) CRF(corticotropin-releasing factor)¿¡ ÀÇÇÑ ACTH release potentiation

À§ÀÇ ÀÛ¿ëÀº V1a or V1b receptor¿¡ ÀÇÇØ Á¶ÀýµÇ¸ç phospholipase C¿Í °ü·ÃÀÖ´Ù.

2) ÇÕ¼º

polypeptide precursorÀÇ ÇüÅ·ΠÇÕ¼ºµÇ´Âµ¥ ¿©±â¿¡´Â neurophysin II¶ó´Â binding protein°ú

copeptinÀ̶ó´Â glycosylated peptide°¡ Æ÷ÇԵȴÙ.

´Ù¸¥ peptide hormone°ú ¸¶Âù°¡Áö·Î »õ·ÎÀÌ ÇÕ¼ºµÈ AVP-neurophysin II precursor´Â

axonÀ» Ÿ°í À̵¿ÇÏ¿© AVP, neurophysin II, copeptinÀ¸·Î ³ª´©¾îÁø´Ù.

neuronÀÌ ÀڱصǸé CaÀÌ À¯ÀԵǾî neurosecretory vesicleÀÌ ÇÕÃÄÁ® AVP°¡ systemic

circulationÀ¸·Î ¹æÃâµÈ´Ù.

3) ºÐºñ

* ºÐºñÁ¶Àý

i) "effective" osmotic pressure - 1Â÷Àû Á¶ÀýÀÎÀÚ

supraoptic nucleus±ÙóÀÇ anteromedial hypothalamus¿¡ À§Ä¡ÇÑ osmoreceptors¾Ë·ÁÁø

specialized cells¿¡ ÀÇÇØ controlµÈ´Ù.

ÀÌ osmoreceptor´Â plasma sodium or mannitol°ú °°Àº soluteÀÇ Á¶±×¸¸ º¯È­¿¡µµ ¹Î°¨

ÇÏ´Ù.

plasma osmolality/sodiumÀÌ ¡­280 mosmol/kg or 135 meq/LÀÌÇÏ·Î depressµÇ¸é

water diuresis¸¦ ÀÏÀ¸Å°±â À§ÇØ plasma AVP´Â ¾ïÁ¦µÈ´Ù.

¹Ý´ë·Î plasma osmolality/sodiumÀÌ ¡­295 mosmol/kg and 143 meq/LÀÌ»óÀÌ µÇ¸é

maxium antidiuresis¸¦ ÀÏÀ¸Å°±â À§ÇØ AVP´Â Áõ°¡ÇÑ´Ù.

ii) baroregulation - minor importance

AVP secretionÀº blood volume or pressureÀÇ acute change¿¡µµ ¿µÇâÀ» ¹Þ´Â´Ù.

baroregulation˼ cardiac atria, aorta, carotid artery˂ transmural pressure receptors

¿¡¼­ ±â¿øÇÑ neuronal afferents¿¡ ÀÇÇØ ÁÖ·Î Á¶ÀýµÈ´Ù.

baroreceptor -> vagus & glossopharyngeal nerve

-> brain stemÀÇ nucleus tractus solitarisus

-> hypothalamusÀÇ paraventricular & supraoptic nucleii

ÀÌ pathway´Â blood volume or pressure°¡ 10-20%ÀÌ»ó °¨¼ÒÇÒ ¶§ tonic inhibitory toneÀ»

À¯ÁöÇÔÀ¸·Î½á AVP release¸¦ Á¶ÀýÇÑ´Ù.

iii) other nonosmotic variables: nausea, hypoglycemia, glucocorticoid deficiency,

smoking, and, possibly, hyperangiotensinemia

¿¹> nausea -> medullaÀÇ emetic center¸¦ ÅëÇÏ¿© AVP ºÐºñ¸¦ ÀÚ±ØÇÏ¿©

plasma AVP°¡ 50-100¹è Áõ°¡

4) ´ë»ç

´ëºÎºÐ °£°ú ½ÅÀåÀ» ÅëÇÏ¿© degradationµÇ¸ç ¹Ý°¨±â´Â 10-30ºÐ Á¤µµ µÈ´Ù.

urinary AVP excretionÀÇ ÃøÁ¤Àº plasma AVP ºÐºñ º¯È­ÀÇ reliable indicator°¡ µÇÁö ¸øÇÑ´Ù.

ÀÓ½ÅÁß¿¡´Â placenta¿¡¼­ N-terminal peptidase¸¦ »ý¼ºÇÔÀ¸·Î½á metabolic clearance°¡

3-4¹è Áõ°¡ÇÑ´Ù.