The effect of paraquat on guanylate cyclase activity in relation to morphological changes of guinea pig lungs

Lung ◽  
1979 ◽  
Vol 157 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Shri N. Giri ◽  
Gopal A. Krishna
Keyword(s):  
Guinea Pig ◽  
Guanylate Cyclase ◽  
Morphological Changes ◽  
Cyclase Activity ◽  
Guanylate Cyclase Activity

scholarly journals The metabolism of cyclic nucleotides in the guinea-pig pancreas. Adenylate cyclase and guanylate cyclase

1980 ◽  
Vol 186 (2) ◽  
pp. 499-505 ◽  
Author(s):  
M Lemon ◽  
P Methven ◽  
K Bhoola
Keyword(s):  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Guanylate Cyclase ◽  
Cyclic Nucleotides ◽  
Cyclase Activity ◽  
Dependent Manner ◽  
Guanylate Cyclase Activity ◽  
Triton X ◽  
Dose Dependent ◽  
Significant Activation

Adenylate cyclase from the guinea-pig pancreas was activated in a dose-dependent manner by both secretin and cholecystokinin-pancreozymin, but in contrast with results in other species the hormones were approximately equipotent. All other hormones and transmitter substances tested were without any effect on adenylate cyclase activity. Guanylate cyclase activity was shown to have both particulate and supernatant components in the guinea-pig pancreas. The particulate enzyme, but not the supernatant enzyme, was markedly activated by Triton X-100, and most of the induced activity was released into the supernatant. The supernatant enzyme was specifically Mn2+-dependent, but, even though Mn2+ was maximally effective at a concentration of 3 mM, activity could be raised further by increasing Ca2+ concentration. The particulate enzyme, by contrast, was relatively Mn2+-independent. Activity of the particulate guanylate cyclase was enhanced by phosphatidylserine. The supernatant enzyme displayed classical Michaelis-Menten kinetics, but the particulate enzyme deviated markedly from such kinetics. Under none of the conditions used was any significant activation of guanylate cyclase observed with any of the secretogen hormones or transmitter substances.

scholarly journals Regulation of guanylate cyclase in guinea-pig islets of Langerhans

1974 ◽  
Vol 142 (2) ◽  
pp. 379-384 ◽  
Author(s):  
Simon L. Howell ◽  
William Montague
Keyword(s):  
Guinea Pig ◽  
Islets Of Langerhans ◽  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Phosphodiesterase Inhibitor ◽  
Cyclase Activity ◽  
Insulin Biosynthesis ◽  
Ph Optimum ◽  
Neutral Alumina ◽  
Guanylate Cyclase Activity

1. Guanylate cyclase activity was determined in homogenates of guinea-pig islets of Langerhans by measurement of the conversion of [α-32P]GTP into cyclic [32P]GMP, the reaction products being separated on columns of neutral alumina. 2. The pH optimum of the enzyme was 7.3; it showed a requirement for bivalent cations, the effectiveness of the cations tested being Mn2+»Ca2+>Mg2+. 3. About 70% of enzyme activity was sedimented by centrifugation at 105000g for 60min; activity was increased 2.3-fold by treatment of homogenates with 0.1% Triton X-100. 4. Guanylate cyclase activity of homogenates was increased by acetylcholine, secretin or pancreozymin, but was inhibited by adrenaline, noradrenaline or ATP. Insulin, glucagon, prostaglandins E1 or E2, glucose, F-, diazoxide or glibenclamide were ineffective. 5. Determination of cyclic GMP amounts in islets by radioimmunoassay showed a basal concentration of 2.0pmol/mg of protein, which was increased by incubation of the islets in the presence of acetylcholine or the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, but was unaffected by glucose. 6. Dibutyryl cyclic GMP had significant stimulatory effects on rates of insulin biosynthesis in isolated rat islets of Langerhans. 7. These results suggest a possible role for cyclic GMP in the regulation of insulin biosynthesis and secretion.

scholarly journals Oxidative-reductive modulation of guinea pig splenic cell guanylate cyclase activity.

1978 ◽  
Vol 253 (9) ◽  
pp. 3143-3152
Author(s):  
M.K. Haddox ◽  
J.H. Stephenson ◽  
M.E. Moser ◽  
N.D. Goldberg
Keyword(s):  
Guinea Pig ◽  
Guanylate Cyclase ◽  
Cyclase Activity ◽  
Guanylate Cyclase Activity ◽  
Splenic Cell
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