Inhibitory guanine nucleotide regulatory protein α-subunits in brain of spontaneously hypertensive rats

Life Sciences ◽  
1996 ◽  
Vol 59 (25-26) ◽  
pp. 2167-2171 ◽  
Author(s):  
Tatsuya Ichida ◽  
Kazuo Takeda ◽  
Susumu Sasaki ◽  
Masao Nakagawa ◽  
Kinya Kuriyama
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Regulatory Protein ◽  
Guanine Nucleotide ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Guanine Nucleotide Regulatory Protein ◽  
Α Subunits

Enhanced lipolysis is not evident in adipocytes from exercise-trained SHR

1986 ◽  
Vol 61 (4) ◽  
pp. 1301-1308 ◽  
Author(s):  
R. E. Shepherd ◽  
M. D. Bah ◽  
K. M. Nelson
Keyword(s):  
Binding Sites ◽  
Spontaneously Hypertensive Rats ◽  
Lipolytic Activity ◽  
Regulatory Protein ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Fat Cell ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto ◽  
Guanine Nucleotide Regulatory Protein

Adipocytes from spontaneously hypertensive rats (SHR) are not as responsive to isoproterenol or dibutyryl adenosine 3′,5′-cyclic monophosphate (cAMP) stimulation compared with Sprague-Dawley or Wistar-Kyoto rats. Lipolytic activity in adipocytes from trained normotensive rats was enhanced in response to 1 microM isoproterenol and 0.5 mM dibutyryl cAMP but not in adipocytes from trained SHR. Decreases in isoproterenol-stimulated (1 microM) cAMP accumulation were evident in adipocytes from trained normotensive rats but not in adipocytes from trained SHR. Basal and agonist-induced lipolysis in fat cells isolated from both normotensive rats and SHR immediately following a 60-min run was increased in both sedentary and trained rats. Adenylate cyclase activity in fat cell membranes was blunted in sedentary and trained SHR both in the absence and presence of 100 microM 5′-guanylyl imidophosphate. No apparent differences existed in antagonist affinity of binding sites for the antagonist dihydroalprenolol in normal rats or SHR. Evidence for a change in affinity of agonist isoproterenol might be indicated based on the enhanced potency of isoproterenol to stimulate lipolysis in trained normal rats. beta-Adrenergic receptor density and antagonist affinity were not different in normotensive rats and SHR in response to training. However, displacement of [3H]dihydroalprenolol in adipocytes from SHR required greater concentrations of isoproterenol compared with adipocytes from normotensive rats, further suggestive of increased agonist affinity of binding sites in normal rats. These data suggest a postreceptor lesion of the lipolytic pathway in adipocytes from spontaneously hypertensive rats, possibly at the guanine nucleotide regulatory protein level.(ABSTRACT TRUNCATED AT 250 WORDS)

StAR expression and the long-term aldosterone response to high-potassium diet in Wistar-Kyoto and spontaneously hypertensive rats

2007 ◽  
Vol 292 (1) ◽  
pp. E16-E23 ◽  
Author(s):  
Barbara Peters ◽  
Philipp Teubner ◽  
Susanne Clausmeyer ◽  
Tanja Puschner ◽  
Christiane Maser-Gluth ◽  
...  
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Regulatory Protein ◽  
Mrna Levels ◽  
Ang Ii ◽  
Hypertensive Rats ◽  
High Potassium ◽  
Spontaneously Hypertensive ◽  
Aldosterone Production ◽  
Wistar Kyoto

ANG II and potassium are known to increase steroidogenic acute regulatory protein (StAR) levels. However, a corresponding increase in StAR mRNA levels has so far been observed only in response to ANG II. We therefore studied the regulation of adrenal StAR mRNA expression in the context of dietary potassium-stimulated aldosterone production. Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were fed a diet containing either 1 or 4% KCl for 5 days. The high-potassium diet increased StAR mRNA levels within the zona glomerulosa in both strains, as demonstrated by in situ hybridization. However, aldosterone production increased in WKY but not in SHR (WKY: from 22.8 ± 4.8 to 137 ± 25 ng/100 ml, P < 0.001, vs. SHR: from 29 ± 3.8 to 51 ± 10.2 ng/100 ml, not significant). This increase was associated with an increase in Cyp11b2 mRNA levels in WKY (3-fold; P < 0.001) but not in SHR. In both strains, the 4% KCl diet was associated with increased plasma renin-independent aldosterone production, as indicated by the marked increase of the aldosterone-to-renin ratios (from 1.4 ± 0.3 to 9 ± 3 in WKY and from 3 ± 1 to 14 ± 5 in SHR; P < 0.002). We conclude that an increase of StAR mRNA levels within the outer cortex is involved in the long-term adrenal response to potassium. This increase alone is not sufficient to increase aldosterone production in the presence of normal Cyp11b2 mRNA levels.

scholarly journals Enhanced expression of inhibitory guanine nucleotide regulatory protein in spontaneously hypertensive rats. Relationship to adenylate cyclase inhibition

1992 ◽  
Vol 288 (1) ◽  
pp. 79-85 ◽  
Author(s):  
M B Anand-Srivastava
Keyword(s):  
Adenylate Cyclase ◽  
G Protein ◽  
G Proteins ◽  
Spontaneously Hypertensive Rats ◽  
Regulatory Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Heart Sarcolemma

We have previously shown that the stimulatory effects of guanine nucleotides, N-ethylcarboxamide-adenosine and other agonists on adenylate cyclase activity were diminished in aorta and heart sarcolemma of spontaneously hypertensive rats (SHR) [Anand-Srivastava (1988) Biochem. Pharmacol. 37, 3017-3022]. In the present studies, we have examined whether the decreased response of these agonists is due to the defective GTP-binding proteins (G-proteins) which couple the receptors to adenylate cyclase, and have therefore measured the levels of G-proteins in aorta and heart from SHR and their respective Wistar-Kyoto (WKY) controls by using pertussis toxin (PT)- and cholera toxin (CT)-catalysed ADP-ribosylations and immunoblotting techniques using specific antibodies against G-proteins. The labelling with [32P]NAD+ and PT identified a 40/41 kDa protein in heart and aorta from WKY and SHR and was significantly increased in the hearts (approximately 100%) and aorta (approximately 30-40%), from SHR as compared with WKY. Immunoblotting revealed an increase in the levels of the G-protein alpha-subunits Gi alpha-2 and Gi alpha-3 in heart and Gi alpha-2 in aorta, whereas no change in Go alpha was observed in heart from SHR and WKY. On the other hand, no differences were observed in CT labelling or immunoblotting of stimulatory G-protein (Gs) in heart and aorta from WKY and SHR. In addition, CT stimulated the adenylate cyclase activity in heart sarcolemma from WKY and SHR to a similar extent. These results were correlated with adenylate cyclase inhibition and stimulation by various hormones. Angiotensin II (AII), atrial natriuretic factor (ANF) and oxotremorine-mediated inhibition was found to be greater in SHR as compared with WKY, whereas the stimulatory effects of adrenaline, isoprenaline, dopamine and forskolin were diminished in SHR aorta as compared to WKY. These results indicate that regulatory protein G(i) is more expressed in SHR, which may be associated with the decreased responsiveness of stimulatory hormones and increased sensitivity of inhibitory hormones to stimulate/inhibit adenylate cyclase activity. It may thus be suggested that the enhanced G(i) activity may be one of the mechanisms responsible for the diminished vascular tone and impaired myocardial functions in hypertension.

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