Influence of caffeine on blood pressure and platelet aggregation.

OBJECTIVE: Studies have demonstrated that methylxanthines, such as caffeine, are A1 and A2 adenosine receptor antagonists found in the brain, heart, lungs, peripheral vessels, and platelets. Considering the high consumption of products with caffeine in their composition, in Brazil and throughout the rest of the world, the authors proposed to observe the effects of this substance on blood pressure and platelet aggregation. METHODS: Thirteen young adults, ranging from 21 to 27 years of age, participated in this study. Each individual took 750 mg/day of caffeine (250 mg tid), over a period of seven days. The effects on blood pressure were analyzed through the pressor test with handgrip, and platelet aggregation was analyzed using adenosine diphosphate, collagen, and adrenaline. RESULTS: Diastolic pressure showed a significant increase 24 hours after the first intake (p<0.05). This effect, however, disappeared in the subsequent days. The platelet aggregation tests did not reveal statistically significant alterations, at any time during the study. CONCLUSION: The data suggest that caffeine increases diastolic blood pressure at the beginning of caffeine intake. This hypertensive effect disappears with chronic use. The absence of alterations in platelet aggregation indicates the need for larger randomized studies.

Comportamento da pressão arterial em filhos de normotensos e filhos de hipertensos submetidos a estímulos pressóricos / Arterial blood pressure responses in children of normotensive and hypertensive parents submitted to pressor tests

OBJETIVO - Comparar a pressão arterial (PA) basal e as respostas a estímulos pressóricos de filhos de normotensos e filhos de hipertensos. MÉTODOS - Foram examinados 32 adolescentes, do sexo masculino, brancos, na faixa etária entre 13 e 18 anos, sendo que 16 eram filhos de hipertensos e 16 filhos de normotensos. Para cada indivíduo foi aferida a PA basal seguida da aplicaçäo de três testes pressóricos: teste do exercício isométrico com o handgrip, teste pressor ao frio e teste do exercício aritmético mental. Para a aferiçäo da PA foi utilizado um dispositivo oscilométrico, digital, previamente calibrado. Resultados - Os filhos de hipertensos exibiram valores basais de PA, tanto sistólica quanto diastólica, maiores que os filhos de normotensos (p "menor" 0,10). Quanto aos testes pressóricos, as respostas foram maiores nos filhos de hipertenso, porém somente a resposta da PA diastólica ao teste do exercício aritmético mental alcançou significância estatística (p "menor" 0,10). Conclusäo - Os resultados obtidos indicam a necessidade de atençäo especial às crianças e adolescentes com antecedentes familiares de hipertensäo.

[Blood pressure responses in children of normotensive and of hypertensive parents treated with pressor stimulus]. / Comportamento da pressão arterial em filhos de normotensos e filhos de hipertensos submetidos a estímulos pressóricos.

PURPOSE: To compare cardiovascular reactivity in adolescents with and without family history of hypertension. METHODS: Thirty two subjects, males, students, aging between 13 to 18 years old were examined. One half of them had no family history of hypertension and the other half had at least one hypertensive parent. Basal blood pressure level was obtained before the application of the following selected tests: isometric handgrip exercise test, cold pressor test and arithmetic mental stress test. The blood pressure values were obtained by a digital, oscilometric device, previously calibrated. RESULTS: The subjects with family history of hypertension exhibited higher basal levels of both systolic and diastolic blood pressure (p < 0.10). Concerning the tests applied, the subjects with family history of hypertension also exhibited higher responses, but only the responses of the diastolic blood pressure to the mental stress test was statistically significant (p < 0.10). CONCLUSION: Our findings point to the need of a special follow-up of children with a family history of hypertension.

[Prevalence and sociocultural and economic aspects of hypertension in a health center of the northern area of Manaus]. / Prevalência e aspectos sócio-culturais e econômicos da hipertensão arterial em centro de saúde da zona norte de Manaus.

PURPOSE: To verify the prevalence and the possible sociocultural and economic factors involved in high blood pressure (HBP), intending to contribute to the elaboration of public health programs. METHODS: The blood pressure of 1,766 individuals, aging 13 years old or more, was measured by the auscultatory method, using a stethoscope and a sfigmomanometer. It was included in the HBP group, the individual presenting blood pressure above 140 x 90 mmHg in two measurements on different occasions. These individuals answered a form searching for sociocultural and economic aspects. RESULTS: Among the individuals examined, 76 were considered to have HBP. There was an increase on the prevalence of HBP with an increase of age, being the greatest among the individuals aging 49 years or more. It was observed significant association between age and HBP (p < 0.05), but the same did not happen with sex or skin color. In most part of the individuals with HBP, it was observed low family income and low educational level. Half of the HBP patients were used to eat with salt and fat. CONCLUSION: The educational level, economic status, and sociocultural habits of a person constitute factors that must be considered in the development of public health programs for control and reduction of the prevalence of HBP.

[Estimation of blood pressure in children using a regression equation]. / Estimativa da pressão arterial em crianças por equação de regressão.

Blood pressure was determined at the Instituto de Educação do Rio de Janeiro in apparently normal school children, aged 5 to 12 years. Among the 2045 school children, 12 were considered unfit for the study as they presented symptoms of illnesses which could affect the results. The total number was, then, reduced to 2033 children--689 boys and 1344 girls. The blood pressure was measured by auscultatory method of the right arm with children lying supine. A mercury manometer and cuffs of adequate sizes were used. A record of pulse rate, weight and height was also obtained. Normal maximum limits of blood pressure was established according to the 95th percentile. The correlations of weight, height and blood pressure were determined and a regression equation could be elaborated; thus, one can obtain an estimated blood pressure from a child's weight and height.