What question did this study set out to answer?

To determine whether angiotensin I is locally converted to active angiotensin II within the rat subfornical organ to elicit functional neuronal and behavioral responses.

June 1, 1999AJP Regulatory Integrative and Comparative Physiology

Functional evidence for subfornical organ-intrinsic conversion of angiotensin I to angiotensin II

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Population

Rat subfornical organ (SFO) in vitro slice preparation (n=25 neurons tested) and water-sated rats in vivo

Comparison

Angiotensin I and Angiotensin II applied via… vs Saline injection

Design

Preclinical

Follow-up

1 h (for water intake)

Authors

MRMatthias RauchThe University of Melbourne HSHerbert SchmidNovartis (Switzerland)

Discussion

Member takes

Implication

May inform central thirst mechanisms in rodents; leaves open translation to human fluid balance or hypertension.

Key Points

To determine whether angiotensin I is locally converted to active angiotensin II within the rat subfornical organ to elicit functional neuronal and behavioral responses.
Extracellular electrophysiological recordings were performed in rat subfornical organ brain slices during superfusion with angiotensin I and II alone or combined with captopril or losartan.
In vivo dipsogenic assays measured 1-hour water intake in water-sated rats after subcutaneous injection of equimolar angiotensin I or II (200 µl, 2 x 10⁻⁴ M), with or without captopril pretreatment.
Angiotensin I and II excited approximately 75% of tested neurons (n=25) at 10⁻⁸ to 10⁻⁷ M with matched response latency, duration, and threshold concentrations (10⁻⁹ M).
Captopril (10⁻⁴ M, n=8) blocked angiotensin I-induced excitation, while losartan (10⁻⁵ M, n=6) eliminated excitations induced by both peptides.
Equimolar subcutaneous injections increased 1-hour water intake to 2.4 ± 0.5 ml (n=16) for angiotensin I and 2.7 ± 0.4 ml (n=20) for angiotensin II versus 0.07 ± 0.06 ml in controls, an effect suppressed by high-dose captopril.

Structured PICO

Population

Rat subfornical organ (SFO) in vitro slice preparation (n=25 neurons tested) and water-sated rats in vivo

Intervention

Angiotensin I (ANG I) and Angiotensin II (ANG II) applied via superfusion (in vitro) or subcutaneous injection (in vivo), with or without captopril or losartan

Comparator

Saline injection (for in vivo water intake experiments)

Outcome

Neuronal excitation (firing rate, duration, and latency) in vitro and water intake in vivosurrogate

This study provides direct functional evidence for a subfornical organ-intrinsic renin-angiotensin system capable of locally converting ANG I to functionally active ANG II.

Cite This Study

Rauch et al. (1999) studied this question.

synapsesocial.com/papers/6a816ba7adfa6baaaee1d4cc https://doi.org/10.1152/ajpregu.1999.276.6.r1630

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Functional evidence for subfornical organ-intrinsic conversion of angiotensin I to angiotensin II

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Functional evidence for subfornical organ-intrinsic conversion of angiotensin I to angiotensin II

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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