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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The adrenergic receptors have been implicated in the pathogenesis of essential hypertension. We hypothesized that hypertension is associated with variants at the beta2-adrenergic receptor locus and at one of the alpha2-adrenergic receptor loci. In unrelated individuals, we measured untreated blood pressure and characterized each subject as hypertensive or normotensive. We then used genomic DNA to identify beta2- and alpha2c10-adrenergic receptor restriction fragment length polymorphisms. In 175 subjects (49 percent with hypertension, 55 percent black), both hypertension and race were associated with genotype at the beta2 locus (chi2 for hypertension = 11, P = .004, chi2 for race = 8.8, P = .012). The association with hypertension persisted in each race group separately (blacks only: chi2 = 9.6, P = .008; whites only; chi2 = 14.2, P = .001). This association persisted in a logistic model that controlled for race (P = .01). Genotype was also significantly associated with baseline systolic, diastolic, and mean arterial blood pressures (P = .05, .01, and .02, respectively). These data suggest that the beta2-adrenergic receptor gene is a candidate gene for hypertension in blacks and whites. We also genotyped subjects at the alpha2-adrenergic receptor coded on chromosome 10. There was no association between hypertension and genotype at the alpah2c10 locus in the total group or in blacks, but there was significant association in whites (chi2 = 6.7, P = .03). These data suggest that the beta2- and alph2c10-adrenergic receptor genes may contribute, in a race-specific manner, to the inheritance of essential hypertension. Linkage studies in related individuals are needed to confirm these findings.
Hypertension 1996 Jun
PMID:Association of hypertension with beta2- and alpha2c10-adrenergic receptor genotype. 864 26

For the past decade, hypertension research has shifted strongly in the direction of molecular genetics. The success stories are the monogenic hypertensive syndromes. Classic linkage analyses has located the responsible genes for glucocorticoid-remediable aldosteronism, Liddle syndrome, and apparent mineralocorticoid excess. The genes have been cloned and their function elucidated. Other monogenic syndromes are currently being intensively studied. However, in the area of primary hypertension, the successes have relied on the candidate gene approach. Allelic variants in the genes for angiotensinogen, alpha-adducin, beta2-adrenergic receptor, the G-protein beta3-subunit and the T594M mutation in the beta-subunit of the epithelial sodium channel have been identified; however, the importance of these allelic variants to primary hypertension as a whole, is not yet clear. A variant in the angiotensin-converting enzyme gene could not, initially, be convincingly associated with hypertension, but more recent analyses suggest an influence of the deletion allele on blood pressure in men, but apparently not in women. In all likelihood we are dealing with many genes with small effects. Affected sibling pair linkage analyses will probably not be successful in identifying the loci of these genes. To find new genes, novel approaches will be necessary, including searching for quantitative trait loci linked to blood pressure in normotensive persons, haplotype sharing methodology in trios and family units, the use of better study designs, and the investigation of isolated populations. Finally, rethinking the phenotype 'hypertension' and its intermediates must also receive priority.
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PMID:Molecular genetics of human hypertension. 988 71

Glucocorticoids and catecholamines exert important effects on cardiovascular physiology and metabolism. Variants of the glucocorticoid receptor gene (GRL) and the beta2-adrenergic receptor gene (ADRB2) have been associated with high blood pressure and obesity. These genes are close on human chromosome 5q31-5q32, and we undertook a linkage analysis of this region in 264 families from the general population in relation to systolic and diastolic blood pressure, body mass index, weight, height, and pulse rate. All family members were genotyped at four microsatellite loci (D5S207, D5S210, D5S519, and D5S119) located on chromosome 5q31-5q33.3. Using quantitative identity-by-descent sibling pair linkage analysis, we found that at no loci was genetic similarity associated with phenotypic similarity for systolic and diastolic blood pressure, body mass index, weight, height, or pulse rate. Although it is not possible to exclude the influence of specific combinations of certain GRL and ADRB2 polymorphisms, the absence of significant linkage in our population argues against a role for GRL or ADRB2 in physiological variation of blood pressure and body mass index.
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PMID:Linkage analysis of glucocorticoid and beta2-adrenergic receptor genes with blood pressure and body mass index. 1019 65

The beta2-adrenergic receptor (beta2-AR) belongs to the group of G-protein coupled receptors and is present mainly on skeletal and cardiac muscle cells and lymphocytes. The gene encoding beta2-AR (ADRB2) displays a moderate degree of heterogeneity in the human population. The distribution of polymorphisms at amino acid positions 16, 27 and 164 is changed in asthma, hypertension and obesity. We have earlier reported a decreased density of the beta2-AR on peripheral blood mononuclear cells and the presence of beta2-AR antibodies in patients with MG. Since certain polymorphisms affect the function of the beta2-AR, it was of interest to analyse these in MG. Using allele-specific polymerase chain reaction amplification, we revealed an over-representation of homozygosity for Arg16 and a lower prevalence of homozygosity for Gly16 in MG patients compared with healthy individuals. The increased frequency of homozygosity for Arg16 was due to a contribution from patients with generalized MG but not from patients with only ocular disease. Homozygosity for Glu27 was negatively associated with both the presence of beta2-AR antibodies and severity of disease. Moreover, acetylcholine receptor (AChR) antibodies were more often present in patients being homozygous for Gln27. Our results imply that homozygosity for Arg16 confers susceptibility to generalized MG, and that certain polymorphisms at amino acid position 27 are associated with subgroups of patients.
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PMID:beta2-adrenergic receptor gene polymorphisms in myasthenia gravis (MG). 1060 77

There are ethnic differences in the prevalence and severity of hypertension and asthma and in beta-2 adrenergic receptor (BAR2)-mediated vascular responses. Two common polymorphisms of the human BAR2, Arg16 to Gly and Gln27 to Glu, are associated with alterations in BAR2 response, both in vitro and in vivo. Ethnic differences in disease manifestations and responses to treatment may be explained by the altered frequency of BAR2 polymorphisms. To determine the relative frequencies of the Arg16 to Gly and Gln27 to Glu BAR2 polymorphisms in different ethnic groups we studied 415 (123 African-American, 188 Caucasian-American and 104 Chinese) healthy individuals. There was a marked interethnic difference in the frequency of the BAR2 polymorphisms among the ethnic groups. The Glu27 allele was more frequent in Caucasian-American (34.8%) than in African-American individuals (20.7%) (P = 0.0001) and much less frequent in Chinese individuals (7.2%) (P = 0.0001 versus African-American or Caucasian-American). The homozygous Glu27 genotype was more frequent in Caucasian-American (15.4%) than African-American individuals (4.9%) (P = 0.003) and was not observed in Chinese. The Gly16 allele (54.3% versus 41.3%) and homozygous genotype (35.1% versus 18.3%) were more common in Caucasian-American than Chinese individuals (P = 0.003 for both). There is a marked ethnic difference in the frequency of these two common BAR2 polymorphisms among African-American, Caucasian-American and Chinese individuals, with a markedly reduced frequency of the Glu27 polymorphism, the polymorphism associated with resistance to desensitization and increased BAR2 responses, in African-American and Chinese individuals. Such ethnic genotypic differences may explain previously observed alterations in the response to the BAR agonists in different ethnic groups.
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PMID:Frequency of functionally important beta-2 adrenoceptor polymorphisms varies markedly among African-American, Caucasian and Chinese individuals. 1078 Feb 71

A genetic linkage study of young-onset hypertension was performed on data from 59 nucleus families of Han Chinese residing in Taiwan. Thirty seven microsatellite markers near 18 hypertension candidate genes were genotyped. In a nonparametric identity-by-descent sibpair analysis, a positive linkage signal (defined as P<0.05) was found for four microsatellite markers, viz., D1S1612 (P=0.0162), D1S547 (P=0.0263), D8S 1145 (P= 0.0284), and D17S2193 (P=0.0256), which were located near genes for atrial natriuretic peptide (NPPA)/glucose transporter 5 (SLC2A5), angiotensinogen (AGT), lipoprotein lipase (LPL), and angiotensin-conveting enzyme (DCP1), respectively. Marker D5S1480 located near beta-2-adrenergic receptor (ADRB2) had a borderline P value (P=0.0785) for the positive signal. Comprehensive genotyping with further markers in these regions is underway to confirm whether these genes are linked to young-onset hypertension.
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PMID:Linkage analysis with candidate genes: the Taiwan young-onset hypertension genetic study. 1107 81

The present study was carried out to ascertain whether beta2-adrenergic receptor stimulation with clenbuterol would attenuate the pulmonary arterial, capillary and venous hypertension in horses performing high-intensity exercise and, in turn, modify the occurrence of exercise-induced pulmonary haemorrhage (EIPH). Experiments were carried out on 6 healthy, sound, exercise-trained Thoroughbred horses. All horses were studied in the control (no medications) and the clenbuterol (0.8 pg/kg bwt, i.v.) treatments. The sequence of these treatments was randomised for every horse, and 7 days were allowed between them. Using catheter-tip-transducers whose in-vivo signals were referenced at the point of the left shoulder, right heart/pulmonary vascular pressures were determined at rest, sub-maximal exercise and during galloping at 14.2 m/s on a 3.5% uphill grade--a workload that elicited maximal heart rate and induced EIPH in all horses. In the control experiments, incremental exercise resulted in progressive significant increments in right atrial as well as pulmonary arterial, capillary and venous (wedge) pressures and all horses experienced EIPH. Clenbuterol administration to standing horses caused tachycardia, but significant changes in mean right atrial or pulmonary vascular pressures were not observed. During exercise performed after clenbuterol administration, heart rate as well as right atrial and pulmonary arterial, capillary and wedge pressures also increased progressively with increasing work intensity. However, these values were not found to be statistically significantly different from corresponding data in the control study and the incidence of EIPH remained unaffected. Since clenbuterol administration also does not affect the transpulmonary pressure during exercise, it is unlikely that the transmural force exerted onto the blood-gas barrier of exercising horses is altered following i.v. clenbuterol administration at the recommended dosage.
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PMID:Clenbuterol administration does not attenuate the exercise-induced pulmonary arterial, capillary or venous hypertension in strenuously exercising Thoroughbred horses. 1109 30

The stimulation of pulmonary beta2-adrenergic receptors causes a decrease in vascular resistance. Thus, the present study was carried out to examine whether concomitant administration of clenbuterol-a beta2-adrenergic receptor agonist, to horses premedicated with furosemide would attenuate the exercise-induced pulmonary capillary hypertension to a greater extent than furosemide alone, and in turn, affect the occurrence of exercise-induced pulmonary hemorrhage (EIPH). Experiments were carried out on six healthy, sound, exercise-trained Thoroughbred horses. All horses were studied in the control (no medications), furosemide (250 mg i.v., 4 h pre-exercise)-control, and furosemide (250 mg i.v., 4 h pre-exercise)+clenbuterol (0.8 microg/kg i.v., 11 min pre-exercise) experiments. The sequence of these treatments was randomized for every horse, and 7 days were allowed between them. Using catheter-tip-transducers whose in-vivo signals were referenced at the point of the left shoulder, pulmonary vascular pressures were determined at rest, sub-maximal exercise, and during galloping at 14.2 m/s on a 3.5% uphill grade--a workload that elicited maximal heart rate. In the control study, incremental exercise resulted in progressive significant (P<0.05) increments in heart rate, right atrial as well as pulmonary arterial, capillary and venous (wedge) pressures, and all horses experienced EIPH. Furosemide administration caused a significant (P<0.05) reduction in mean right atrial as well as pulmonary capillary and venous pressures of standing horses. Although exercise in the furosemide-control experiments also caused right atrial and pulmonary vascular pressures to increase significantly (P<0.05), the increment in mean pulmonary capillary and wedge pressures was significantly (P<0.05) attenuated in comparison with the control study, but all horses experienced EIPH. Clenbuterol administration to standing horses premedicated with furosemide caused tachycardia, but significant changes in right atrial or pulmonary vascular pressures were not discerned at rest. During exercise in the furosemide+clenbuterol experiments, heart rate, mean right atrial as well as pulmonary arterial, capillary and wedge pressures increased significantly (P<0.05), but these data were not different from the furosemide-control experiments, and all horses experienced EIPH as well. Thus, it was concluded that clenbuterol administration is ineffective in modifying the pulmonary hemodynamic effects of furosemide in standing or exercising horses. Because the intravascular force exerted onto the blood-gas barrier of horses premedicated with furosemide remained unaffected by clenbuterol administration, it is believed that concomitant clenbuterol administration is unlikely to offer additional benefit to healthy horses experiencing EIPH.
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PMID:Clenbuterol administration does not enhance the efficacy of furosemide in attenuating the exercise-induced pulmonary capillary hypertension in Thoroughbred horses. 1116 17

Functional analysis of beta 1 and beta 2 adrenergic receptor (AR) subtypes has been made possible by establishing knockout mice (KO) with abolished beta 1 and/or beta 2 AR expression. Neither resting heart rate nor resting blood pressure of beta 1 AR KO, beta 2 AR KO, or beta 1/beta 2 KO differed significantly from those of wild-type mice. The chronotropic response to isoproterenol was significantly attenuated in beta 1 AR KO and beta 1/beta 2 KO, whereas there was no detrimental effect on heart rate in beta 2 AR KO. This suggests that chronotropy is mediated by beta 1 AR. In terms of the vasodilatory response to isoproterenol, there appears to be a graded and additive attenuation of the hypotensive response in beta 1 AR KO, beta 2 AR KO, and beta 1/beta 2 KO. Vascular relaxation is thought to be controlled by both beta 1 AR and beta 2 AR. Tachycardia induced by exercise was significantly attenuated in beta 1 AR KO, and beta 1/beta 2 KO. beta 2 AR KO subjected to treadmill exercise showed significant hypertension, increased oxygen consumption, and ability of long distance running.
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PMID:[Adrenergic receptor and knockout mouse: 1) Beta adrenergic receptor knockout mouse]. 1119 10

For the past decade, hypertension research has shifted strongly in the direction of molecular genetics. The success stories are the monogenic hypertensive syndromes. Classic linkage analyses have located the responsible genes for glucocorticoid-remediable aldosteronism, Liddle syndrome, and apparent mineralocorticoid excess. Furthermore, a recent gain-of-function mutation has recently been described in the gene for the mineralocorticoid receptor. These genes have been cloned and their functions elucidated. Other monogenic syndromes are currently being intensively studied. However, in the area of primary hypertension, the successes have relied on the candidate gene approach. Allelic variants in the genes for angiotensinogen, alpha-adducin, the beta2-adrenergic receptor, the G-protein beta3-subunit, and the T594M mutation in the beta-subunit of the epithelial sodium channel have been identified; however, the importance of these allelic variants to primary hypertension as a whole is not yet clear. Recently, an association approach was employed to implicate the mineralocorticoid receptor gene in salt-sensitivity. Linkage approaches have been attempted and the beta-subunit of the epithelial sodium channel has been linked to hypertension and to blood pressure as a quantitative trait locus. New approaches are necessary to elucidate salt-sensitive hypertension. The analysis of multiple genes simultaneously in terms of a metabolic control analysis may provide a more promising approach.
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PMID:Molecular genetics of salt-sensitivity and hypertension. 1125 40


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