Selective Binding Site for [3H]Prostacyclin on Platelets

Siegl, Adelaide M.; Smith, J B; Silver, Melvin J.; Nicolaou, K. C.; Ahern, David G.

doi:10.1172/jci109292

Cited by 196 publications

(46 citation statements)

References 16 publications

(21 reference statements)

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“…The gand selectivity that is compatible with that of the human prostacyclin receptor. [26][27][28][29] The iloprost treatment of COS-7 cells transiently expressing the receptor dose-dependently stimulated the formation of cAMP, which has been known as an intracellular second messenger of prostacyclin actions. ''2 In addition, the nucleotide and deduced amino acid sequences of the cDNA clone are highly homologous with those of the mouse prostacyclin receptor.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning of human prostacyclin receptor cDNA and its gene expression in the cardiovascular system.

et al. 1994

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Background Prostacyclin elicits a potent vasodilation and inhibition of platelet aggregation through binding to its membrane receptor. The impairment of prostacyclin receptor activity is implicated in various human cardiovascular diseases. In the present study, we succeeded in the isolation and characterization of human prostacyclin receptor cDNA and elucidated its gene expression in human tissues.Methods and Results We isolated a cDNA clone encoding the human prostacyclin receptor from a human lung cDNA library. The isolated cDNA clone encodes a 386-amino acid protein with seven putative transmembrane domains, which belongs to the G protein-coupled receptor superfamily.

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Section: Discussionmentioning

confidence: 99%

Molecular cloning of human prostacyclin receptor cDNA and its gene expression in the cardiovascular system.

et al. 1994

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“…Washed platelets were suspended in Hanks' balanced salt solution lacking calcium and magnesium salts but including 5 mM NaHepes/0.5 mM 1-methyl-3-isobutylxanthine, pH 7.6, to a concentration of =0.25 mg/ml. Duplicate or triplicate aliquots of the platelet suspension (0.38 ml), dispensed into 12 x 75 mm polypropylene tubes, were incubated for 30 min at 37°C to allow basal cAMP levels to equilibrate. Drugs were added in a volume of 0.40 ml.…”

Section: Methodsmentioning

confidence: 99%

Platelets of pseudohypoparathyroid patients: Evidence that distinct receptor-cyclase coupling proteins mediate stimulation and inhibition of adenylate cyclase

Motulsky¹,

Hughes²,

Brickman³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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We studied platelets of patients with the genetic disorder pseudohypoparathyroidism (PHP) to test whether the nucleotide-binding proteins mediating stimulation of adenylate cyclase (termed NS) are identical to those mediating inhibition of cyclase (termed Ni). Functional responses to hormones that work through stimulation of adenylate cyclase are blunted in PHP patients. The erythrocytes of many of these patients (PHP-Ia) have previously been shown to have decreased Ns activity whereas those of other PHP patients (PHP-Ib) have normal Ns activity. We find that this decreased Ns activity (measured by the ability to restore adenylate cyclase activity to membranes prepared from S49 cyccells) also occurs in the platelets of PHP-Ia but not of PHP-Ib patients. Platelets from both groups of patients accumulate less cAMP in response to prostacyclin than do platelets from control subjects. In contrast to the decreased Ns function in patients with PHP-Ia, we find that Ni function in platelets is similar in these patients and control subjects in several types of experiments: (i) epinephrine-mediated inhibition ofprostacyclin-stimulated cAMP production in intact platelets; (ii) the affinity of platelet a%-adrenergic receptors for epinephrine, as determined by competition for [3H]yohimbine binding; (iii) the decrease in receptor affinity for epinephrine produced by Na+ and GTP; and (iv) METHODSPatients. Seven patients with PHP were studied; these were the same patients reported previously (7). Previous assays demonstrated decreased activity of erythrocyte N, in three of the patients (PHP-Ia) but not in four others (PHP-Ib) (7). Control platelets were obtained from healthy men (ages 22-45) who had taken no medication for at least 1 wk.Platelets. Blood was drawn into 60-ml plastic syringes containing 6 ml of 3.8% sodium citrate and centrifuged at 300 X g for 20 min, and the platelet-rich plasma was removed. The packed erythrocytes were mixed with an equal volume of 100 mM NaCl/5 mM EDTA/50 mM Tris-HCl, pH 7.5, and were centrifuged twice. The platelet-rich plasma and the two extracts were combined and centrifuged at 5,000 X g for 10 min and the pellet was washed twice by the same procedure. Determination of cAMP accumulation and some of the radioligand binding assays were carried out with intact platelets suspended in 50 mM Tris-HCl/100 mM NaCV5 mM EDTA, pH 7.5. In other raAbbreviations: PHP, pseudohypoparathyroidism; Ni, nucleotide binding unit coupled to inhibition ofadenylate cyclase; N,, nucleotide binding unit coupled to stimulation ofadenylate cyclase; PGI2, prostaglandin I2 or prostacyclin. 4193The publication costs ofthis article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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“…Binding of the agonist to the low-a nity receptors (Kd in mM ranges) increases the cAMP level in platelets, which inhibits platelet aggregation. 137,138 Binding of the agonist to the high-a nity receptors also increases cAMP levels, probably in a compartmentalized manner and in a smaller quantity when compared with the synthesis of the compound through the lowa nity binding. 140 Also, the synthesis of cAMP by high-a nity prostaglandin binding is under feedback inhibition by the nucleotide itself.…”

Section: Platelets As Sources Of Active Componentsmentioning

confidence: 99%

Risk factors for atherogenesis and cardiovascular autonomic function in persons with spinal cord injury

et al. 1999

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Persons with spinal cord injury (SCI) have been recognized to have several metabolic changes that adversely impact their risk for cardiovascular disease. An increased prevalence of disorders of carbohydrate metabolism and dyslipidemia may be related predominantly to paralysis with immobilization and associated loss of lean body tissue and gain in relative adiposity. Studies have reported an increased risk of vascular disease in those with SCI. As such, an understanding of the constellation of carbohydrate and lipid changes that occur after SCI is relevant to the clinical practice of medicine in this population. Oral glucose tolerance testing and associated studiesImpaired glucose tolerance and diabetes mellitus are more prevalent in individuals with SCI than in those who are able-bodied. 1 ± 4 In most of the individuals with SCI and abnormal carbohydrate tolerance, resistance to insulin mediation of glucose uptake by peripheral tissues may be demonstrable. In the presence of insulin resistance, the normal homeostatic response to glucose challenge is increased pancreatic b-cell secretion of insulin. If the compensatory response of the pancreas is insu cient to control the serum glucose concentration, worsening of carbohydrate tolerance will ensue.Bauman et al 3 performed a 75 g oral glucose tolerance test in 100 male veterans with SCI and in 50 able-bodied veteran controls. According to criteria established by the World Health Organization, 5 22% of those with SCI were diabetic whereas only 6% of the control group were diabetic. Eighty-two per cent of the controls had normal oral glucose tolerance, compared with 38% of those with quadriplegia and 50% of those with paraplegia. Subjects with SCI had signi®cantly higher mean plasma glucose and insulin values at several points during the oral glucose tolerance test when compared with controls ( Figure 1). In subgroups, determinants of insulin sensitivity were measured: per cent lean body mass, per cent fat mass, and cardiopulmonary ®tness. Values for insulin sensitivity were linearly related with those of ®tness (VO 2 max) determined from a progressive incremental upper-body exercise stress test. Insulin sensitivity was suggestively correlated with lean body mass, and negatively correlated with body fat. Thus, in a relatively small subgroup of untrained subjects with paraplegia, the strongest determinant of insulin sensitivity was cardiopulmonary ®tness.In 201 non-veteran subjects with SCI, Bauman et al 2 studied the relationship of oral carbohydrate tolerance after a 75 g glucose load to several variables, including level and completeness of lesion, gender, ethnicity, age, duration of injury, and anthropometric measures. Of the total group, 27 (13%) had diabetes mellitus and 56 (29%) had impaired glucose tolerance. 2,6 The subjects with complete tetraplegia had sign®cantly worse carbohydrate tolerance (Figure 2) and were more frequently classi®ed with a disorder of carbohydrate tolerance than the other neurological de®cit subgroups. 2 There were no signi®cant gend...

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Selective Binding Site for [3H]Prostacyclin on Platelets

Cited by 196 publications

References 16 publications

Molecular cloning of human prostacyclin receptor cDNA and its gene expression in the cardiovascular system.

Molecular cloning of human prostacyclin receptor cDNA and its gene expression in the cardiovascular system.

Platelets of pseudohypoparathyroid patients: Evidence that distinct receptor-cyclase coupling proteins mediate stimulation and inhibition of adenylate cyclase

Risk factors for atherogenesis and cardiovascular autonomic function in persons with spinal cord injury

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