Abstract
Angiotensin II (ANG II) and arginine vasopressin (AVP) act on area postrema (AP) neurons to modulate the baroreflex. Because activation of AP neurons by either ANG II or AVP increases intracellular free Ca2+ concentrations ([Ca2+](i)), the goal of this study was to analyze the factors affecting the [Ca2+](i) responses to ANG II and AVP. Neurons were recovered from 14- to 16-day old rats and studied after 8-14 days in culture by use of the microscopic digital image analysis for fura 2-loaded cells. The effects of ANG II (100 nM) and AVP (100 nM) on [Ca2+](i) were determined in normal (2 mM) and low (<10 nM) extracellular Ca2+ concentrations. In 143 of 240 neurons, ANG II increased [Ca2+](i) 4.65-fold after 20 s, and a similar response was observed in the absence of extracellular Ca2+ (3.65-fold after 20 s). After 60 s of observation, steady-state levels of increased [Ca2+](i) were still present under both conditions. Pretreatment with AT1 antagonist or pertussis toxin abolished the response to ANG II. AVP also increased [Ca2+](i) (3.6-fold at peak, 20 s) in normal and low extracellular Ca2+. Pretreatment with AVP V1 antagonist or pertussis toxin abolished the response to AVP. This study indicates that ANG II-induced increases in [Ca2+](i) are independent of extracellular Ca2+ concentrations and involve the activation of AT1 receptors and a pertussis toxin-sensitive G protein. Although AVP affects a fewer number of AP neurons, the mechanisms of activation are also independent of extracellular Ca2+ concentration and are mediated by a pertussis toxin-sensitive G protein.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 271 |
| Issue number | 1 40-1 |
| State | Published - Jul 1996 |
| Externally published | Yes |
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Keywords
- AT receptors
- protein kinase C
- V receptors
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Subcellular mechanisms of angiotensin II and arginine vasopressin activation of area postrema neurons. / Consolim-Colombo, Fernanda M.; Hay, Meredith; Smith, Thomas C.; Elizondo-Fournier, Marta; Bishop, Vernon S.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 271, No. 1 40-1, 07.1996.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Subcellular mechanisms of angiotensin II and arginine vasopressin activation of area postrema neurons
AU - Consolim-Colombo, Fernanda M.
AU - Hay, Meredith
AU - Smith, Thomas C.
AU - Elizondo-Fournier, Marta
AU - Bishop, Vernon S.
PY - 1996/7
Y1 - 1996/7
N2 - Angiotensin II (ANG II) and arginine vasopressin (AVP) act on area postrema (AP) neurons to modulate the baroreflex. Because activation of AP neurons by either ANG II or AVP increases intracellular free Ca2+ concentrations ([Ca2+](i)), the goal of this study was to analyze the factors affecting the [Ca2+](i) responses to ANG II and AVP. Neurons were recovered from 14- to 16-day old rats and studied after 8-14 days in culture by use of the microscopic digital image analysis for fura 2-loaded cells. The effects of ANG II (100 nM) and AVP (100 nM) on [Ca2+](i) were determined in normal (2 mM) and low (<10 nM) extracellular Ca2+ concentrations. In 143 of 240 neurons, ANG II increased [Ca2+](i) 4.65-fold after 20 s, and a similar response was observed in the absence of extracellular Ca2+ (3.65-fold after 20 s). After 60 s of observation, steady-state levels of increased [Ca2+](i) were still present under both conditions. Pretreatment with AT1 antagonist or pertussis toxin abolished the response to ANG II. AVP also increased [Ca2+](i) (3.6-fold at peak, 20 s) in normal and low extracellular Ca2+. Pretreatment with AVP V1 antagonist or pertussis toxin abolished the response to AVP. This study indicates that ANG II-induced increases in [Ca2+](i) are independent of extracellular Ca2+ concentrations and involve the activation of AT1 receptors and a pertussis toxin-sensitive G protein. Although AVP affects a fewer number of AP neurons, the mechanisms of activation are also independent of extracellular Ca2+ concentration and are mediated by a pertussis toxin-sensitive G protein.
AB - Angiotensin II (ANG II) and arginine vasopressin (AVP) act on area postrema (AP) neurons to modulate the baroreflex. Because activation of AP neurons by either ANG II or AVP increases intracellular free Ca2+ concentrations ([Ca2+](i)), the goal of this study was to analyze the factors affecting the [Ca2+](i) responses to ANG II and AVP. Neurons were recovered from 14- to 16-day old rats and studied after 8-14 days in culture by use of the microscopic digital image analysis for fura 2-loaded cells. The effects of ANG II (100 nM) and AVP (100 nM) on [Ca2+](i) were determined in normal (2 mM) and low (<10 nM) extracellular Ca2+ concentrations. In 143 of 240 neurons, ANG II increased [Ca2+](i) 4.65-fold after 20 s, and a similar response was observed in the absence of extracellular Ca2+ (3.65-fold after 20 s). After 60 s of observation, steady-state levels of increased [Ca2+](i) were still present under both conditions. Pretreatment with AT1 antagonist or pertussis toxin abolished the response to ANG II. AVP also increased [Ca2+](i) (3.6-fold at peak, 20 s) in normal and low extracellular Ca2+. Pretreatment with AVP V1 antagonist or pertussis toxin abolished the response to AVP. This study indicates that ANG II-induced increases in [Ca2+](i) are independent of extracellular Ca2+ concentrations and involve the activation of AT1 receptors and a pertussis toxin-sensitive G protein. Although AVP affects a fewer number of AP neurons, the mechanisms of activation are also independent of extracellular Ca2+ concentration and are mediated by a pertussis toxin-sensitive G protein.
KW - AT receptors
KW - protein kinase C
KW - V receptors
UR - http://www.scopus.com/inward/record.url?scp=0029822915&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029822915&partnerID=8YFLogxK
M3 - Article
C2 - 8760201
AN - SCOPUS:0029822915
VL - 271
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6143
IS - 1 40-1
ER -