Pressor Responses to Central Sodium and Ouabain Are Attenuated in Transgenic Rats Deficient in Brain Angiotensinogen

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 728-728
Author(s):  
Bing S Huang ◽  
Detlev Ganten ◽  
Frans Hh Leenen
Keyword(s):  
Antisense Rna ◽  
Renin Angiotensin System ◽  
Dietary Salt ◽  
Transgenic Rats ◽  
Angiotensin System ◽  
Sd Rats ◽  
Pressor Responses ◽  
Freely Moving ◽  
The Brain

P195 Studies using AT 1 -blockers suggest that the brain renin-angiotensin system (RAS) contributes to sympatho-excitation and hypertension by high dietary salt or central sodium loading. To more specifically examine this role of the brain RAS, [TGR (AsrAOGEN)] transgenic rats were used. These rats express an antisense RNA against angiotensinogen mRNA specifically in the brain, and the brain angiotensinogen level is reduced by more than 90%. In freely moving TGR and SD controls, BP and HR responses to intracerebroventricular (icv) infusion (3.8 μl/min for 10 min) of artificial CSF (aCSF) and Na + -rich aCSF (containing 0.2, 0.3 and 0.45 M Na + ) as well as icv injection of ouabain (0.3 and 0.6 μg/2 μl) were assessed. The vasopressin antagonist [d(CH 2 ) 5 Tyr(Me)]AVP (30 μg/kg) was given iv before each icv infusion. Data are means±SEM (n=6, for each).* p<0.05, vs SD rats. Somewhat surprisingly, angiotensin I and II levels of not only hypothalamus but also plasma were lower in TGR vs. SD rats. The clearly attenuated sympatho-excitatory and pressor effects to ouabain and Na + -rich aCSF support the concept that the brain RAS plays an important role in the sympatho-excitatory effects of ouabain and CSF sodium.

scholarly journals Bidirectional asymmetry in the neurovisceral communication for the cardiovascular control: New insights

2017 ◽  
Vol 51 (3) ◽  
pp. 157-167 ◽  
Author(s):  
I Prieto ◽  
AB Segarra ◽  
M Martinez-Canamero ◽  
M De Gasparo ◽  
S Zorad ◽  
...  
Keyword(s):  
Essential Role ◽  
Renin Angiotensin System ◽  
Cardiovascular Function ◽  
Cardiovascular Control ◽  
Functional Connection ◽  
Angiotensin System ◽  
Positive Correlations ◽  
Available Information ◽  
The Brain

AbstractThe cardiovascular control involves a bidirectional functional connection between the brain and heart. We hypothesize that this connection could be extended to other organs using endocrine and autonomic nervous systems (ANS) as communication pathways. This implies a neuroendocrine interaction controlling particularly the cardiovascular function where the enzymatic cascade of the renin-angiotensin system (RAS) plays an essential role. It acts not only through its classic endocrine connection but also the ANS. In addition, the brain is functionally, anatomically, and neurochemically asymmetric. Moreover, this asymmetry goes even beyond the brain and it includes both sides of the peripheral nervous and neuroendocrine systems. We revised the available information and analyze the asymmetrical neuroendocrine bidirectional interaction for the cardiovascular control. Negative and positive correlations involving the RAS have been observed between brain, heart, kidney, gut, and plasma in physiologic and pathologic conditions. The central role of the peptides and enzymes of the RAS within this neurovisceral communication, as well as the importance of the asymmetrical distribution of the various RAS components in the pathologies involving this connection, are particularly discussed. In conclusion, there are numerous evidences supporting the existence of a neurovisceral connection with multiorgan involvement that controls, among others, the cardiovascular function. This connection is asymmetrically organized.

Role of the Brain Renin-angiotensin System in Blood Pressure Regulation

2007 ◽  
Vol 31 (S1) ◽  
pp. 343-346
Author(s):  
M. V. Varoni ◽  
D. Palomba ◽  
M. P. Demontis ◽  
S. Gianorso ◽  
G. L. Pais ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renin Angiotensin System ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
The Brain

Expression of an angiotensin-(1–7)-producing fusion protein produces cardioprotective effects in rats

2004 ◽  
Vol 17 (3) ◽  
pp. 292-299 ◽  
Author(s):  
Robson A. S. Santos ◽  
Anderson J. Ferreira ◽  
Ana Paula Nadu ◽  
Aline N. G. Braga ◽  
Alvair Pinto de Almeida ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Cardiac Contractility ◽  
Renin Angiotensin System ◽  
Transgenic Rats ◽  
Specific Expression ◽  
Angiotensin System ◽  
Angiotensin Converting Enzyme 2 ◽  
Cardioprotective Effects ◽  
Hemodynamic Measurements

Angiotensin-(1–7) [ANG-(1–7)] is a recently described heptapeptide product of the renin-angiotensin system. Because biosynthesis of ANG-(1–7) increases in animals treated with cardioprotective drugs and inactivation of the gene for angiotensin converting enzyme 2 [an enzyme involved in the biosynthesis of ANG-(1–7)] leads to the development of cardiac dysfunction, it has been suggested that ANG-(1–7) has cardioprotective properties. To directly test this possibility, we have generated transgenic rats that chronically overproduce ANG-(1–7) by using a novel fusion protein methodology. TGR(A1–7)3292 rats show testicular-specific expression of a cytomegalovirus promoter-driven transgene, resulting in a doubling of circulating ANG-(1–7) compared with nontransgenic control rats. Radiotelemetry hemodynamic measurements showed that transgenic rats presented a small but significant increase in daily and nocturnal heart rate and a slight but significant increase in daily and nocturnal cardiac contractility estimated by dP/d t measurements. Strikingly, TGR(A1–7)3292 rats were significantly more resistant than control animals to induction of cardiac hypertrophy by isoproterenol. In addition, transgenic rats showed a reduced duration of reperfusion arrhythmias and an improved postischemic function in isolated Langendorff heart preparations. These results support a cardioprotective role for circulating ANG-(1–7) and provide a novel tool for evaluating the functional role of ANG-(1–7).

scholarly journals The Prorenin and (Pro)renin Receptor: New Players in the Brain Renin-Angiotensin System?

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Wencheng Li ◽  
Hua Peng ◽  
Dale M. Seth ◽  
Yumei Feng
Keyword(s):  
Renin Angiotensin System ◽  
Ang Ii ◽  
Future Perspectives ◽  
Vasopressin Release ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Treatment Of Hypertension ◽  
High Level ◽  
The Brain

It is well known that the brain renin-angiotensin (RAS) system plays an essential role in the development of hypertension, mainly through the modulation of autonomic activities and vasopressin release. However, how the brain synthesizes angiotensin (Ang) II has been a debate for decades, largely due to the low renin activity. This paper first describes the expression of the vasoconstrictive arm of RAS components in the brain as well as their physiological and pathophysiological significance. It then focus on the (pro)renin receptor (PRR), a newly discovered component of the RAS which has a high level in the brain. We review the role of prorenin and PRR in peripheral organs and emphasize the involvement of brain PRR in the pathogenesis of hypertension. Some future perspectives in PRR research are heighted with respect to novel therapeutic target for the treatment of hypertension and other cardiovascular diseases.

Aging and the brain renin-angiotensin system: insights from studies in transgenic rats.

2007 ◽  
Vol 74 (Suppl_1) ◽  
pp. S95-S95 ◽  
Author(s):  
D. I Diz ◽  
S. O Kasper ◽  
A. Sakima ◽  
C. M Ferrario
Keyword(s):  
Renin Angiotensin System ◽  
Transgenic Rats ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
The Brain

Differential Effects of Angiotensin II and Angiotensin-(1-7) at the Nucleus Tractus Solitarii of Transgenic Rats with Low Brain Angiotensinogen

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 700-700
Author(s):  
Aurea S Couto ◽  
Ovidiu Baltatu ◽  
Robson A S Santos ◽  
Detlev Ganten ◽  
Michael Bader ◽  
...  
Keyword(s):  
Heart Rate ◽  
Baroreflex Sensitivity ◽  
Renin Angiotensin System ◽  
Nucleus Tractus Solitarii ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Transgenic Rats ◽  
Baroreflex Control ◽  
Sd Rats ◽  
The Brain

P42 The potential importance of permanent alteration of the brain renin-angiotensin system on angiotensin (Ang) II and Ang-(1-7) effects at the level of the nucleus tractus solitarii (NTS) was investigated in transgenic rats with a deficit in brain angiotensinogen production TGR(ASrAOGEN) (TGR). Ang II (10 pmol), Ang-(1-7) (10 pmol) or NaCl (0.9%/ 50 nl) were microinjected into the NTS of urethane-anesthetized TGR (n=28) and Sprague-Dawley (SD, n=22) rats. Mean arterial pressure (MAP) and heart rate (HR) were measured via a femoral artery catheter and the baroreflex control of heart rate was evaluated after increases in MAP induced by phenylephrine (baroreflex bradycardia). Ang II microinjections into the NTS of the TGR induced a higher decrease in MAP and HR (-37 ± 5 mmHg and -69 ± 12.5 beats/min, respectively) in comparison with SD rats (-18 ± 1 mmHg and -51 ± 11 beats/min, respectively). In contrast, changes after Ang-(1-7) microinjections into the NTS of TGR (-6 ± 1 mmHg and -13 ± 5 beats/min) were significantly smaller than that induced in SD (-11 ± 2 mmHg and -24 ± 8 beats/min.). The baroreflex sensitivity was accentuated in TGR in comparison to SD rats (0.69 ± 0.06 vs. 0.44 ± 0.03 ms/ mmHg). Ang II microinjection into the NTS produced similar attenuation in the baroreflex bradycardia in both SD (0.28 ± 0.07 vs. 0.5 ± 0.07 ms/ mmHg, before injection) and TGR (0.44 ± 0.1 vs. 0.82 ± 0.1ms/ mmHg, before injection). Ang-(1-7) microinjection elicited a facilitation of the baroreflex bradycardia in SD (0.62 ± 0.1 vs. 0.4 ± 0.03 ms/ mmHg, before injection). However in TGR, baroreflex bradycardia after Ang-(1-7) was not different from saline microinjection. These results indicate that a permanent inhibition of angiotensinogen synthesis in the brain can lead to a functional up-regulation of Ang II receptors. However, the putative Ang-(1-7) receptors seem to be desensitized in the NTS of these transgenic rats. The alterated baroreflex sensitivity, both before and after Ang microinjection, indicates the functionally relevant decrease in brain Ang in TGR and supports differential regulatory mechanisms for the effects of the two Ang peptides.

Sign in / Sign up

Export Citation Format

Share Document