The effect of caffeine on ambulatory blood pressure in hypertensive patients

Abstract

Because the potential impact of habitual caffeine intake on blood pressure is a controversial issue, a study was carried out to explore the relationship between caffeine and various humoral factors that could account for a coffee-induced rise in blood pressure. Twenty-three hypertensive patients who refrained from caffeine for 2 to 3 weeks were given 250 mg oral caffeine powder dissolved in water. Blood pressure was recorded every 15 min by blood pressure monitor. Caffeine blood level, renin and endothelin were measured before and 1, 2, 3, and 6 h after caffeine intake. Urinary electrolytes and catecholamines were measured under caffeine influence (period I), and for the next 6 h (period II). A significant increase in systolic (P = .017) and diastolic blood pressure (P = .023) occurred in 13 subjects who were 58 +/- 10.4 years old. Nonresponders were younger (44.5 +/- 15.8 years). A statistically significant decrease in heart rate was seen during the first hour after caffeine intake in both responders (P = .008) and nonresponders (P = .004). Marked diuresis and natriuresis were observed during period I in both groups. Renin and endothelin levels were unchanged. Although chronic studies point to development of tolerance to long-term caffeine ingestion, acute studies like the one described are essential to obtain data on the immediate effects that can be of practical importance, especially in the elderly.

Methylxanthines and the Kidney

“…Theophylline and A1 adenosine receptor- selective xanthine derivatives inhibited basolateral HCO 3 conductance in microperfused rabbit proximal convoluted tubules and this effect was mimicked by forskolin and chlorophenylthio-cAMP suggesting that methylxanthines inhibit Na/ HCO 3 cotransport activity by increasing intracellular cAMP (Takeda et al 1993). To the extent that caffeine causes an increase in arterial blood pressure, a potential direct role of blood pressure in inhibiting tubular reabsorption and altering NHE3 distribution needs to be considered (Nussberger et al 1990; Rachima-Maoz et al 1998; Rakic et al 1999). Finally, it should be pointed out that administration of methylxanthines only explores the impact of a reduction in adenosine-mediated effects, and that the consistent stimulatory effect of adenosine suggested by this intervention is therefore not in conflict with the possibility that high concentrations of adenosine may elicit inhibition of proximal tubular transport (Di Sole 2008; Di Sole et al 2003).…”

Cafeína e performance em exercícios anaeróbios

“…Acredita-se ainda que a ação estimulante da cafeína no SNC envolve a estimulação do sistema nervoso simpá-tico, aumentando a liberação e, conseqüentemente, a ação das catecolaminas (Yamada, Nakazato, Ohga, 1989;Rachima-Maoz, Peleg, Rosenthal, 1998). Contudo, essa hipótese é ainda extremamente especulativa, haja vista as grandes limitações que envolvem esse tipo de investigação.…”

A review of non-pharmacological methods to control hypertension in older people

“…There seems little doubt that, when given to caffeine-naive subjects, there is an increase in blood pressure in the order of 3-14 mmHg approximately 30 to 90 minutes after ingestion, 38 which is probably mediated by a rise in vascular resistance. This effect is greater in hypertensives, [38][39][40] smokers, 41 the elderly 42,43 and subjects under stressful conditions. 39,44 The results are less clear for habitual coffee drinkers.…”