The present study was designed to clarify the roles of N-type and P/Q-type calcium channels in the increased sympathetic activity of spontaneously hypertensive rats (SHR/Izm). We also tested in SHR/Izm the contributio...The present study was designed to clarify the roles of N-type and P/Q-type calcium channels in the increased sympathetic activity of spontaneously hypertensive rats (SHR/Izm). We also tested in SHR/Izm the contribution to increased vascular tone of α1A adrenoceptor-linked L-type calcium channels and α1B receptor-mediated calcium mobilization from the sarcoplasmic reticulum. Methods: Six-week-old SHR/Izm and Wistar-Kyoto rats (WKY/Izm) were used. A superior mesenteric arterial preparation was electrically stimulated before and after treatment with ω-conotoxin GVIa (N-type calcium channel blocker [CgTX]) and ω-agatoxinIVa (P/Q-type calcium channel blocker [AgaTX]). Pressor response to norepinephrine was measured before and after treatment with the α1A blocker WB-4101 and the α1B blocker chloroethyl clonidine (CEC). To determine the intracellular calcium store size, the effects of ryanodine on pressor response and caffeine-induced vascular contraction were also tested. Results: Norepinephrine overflow evoked by electrical stimulation was increased in SHR/Izm. CgTX but not AgaTX suppressed the increased NE overflow in SHR/Izm. WB-4101 suppressed the pressor response to norepinephrine in SHR/Izm but not WKY/Izm rats. CEC had no effects on pressor response to norepinephrine in both types of rats. Caffeine-induced contraction to a high potassium-induced maximal contraction ratio was reduced in SHR/Izm. The effect of ryanodine on pressor response was reduced in SHR/Izm. Conclusion: N-type calcium channels but not P/Q-type calcium channels play an important role in the increased sympathetic tone in SHR/ Izm. Although α1A adrenoceptor-linked L-type calcium channels contribute to the increased vascular tone, the intracellular calcium store size was reduced in SHR/Izm.展开更多
The aim of this study was to clarify the response of sympathetic activity to antihypertensive drugs using a mental stress test in hypertensive patients and to determine the effects of antihypertensive drugs on the sym...The aim of this study was to clarify the response of sympathetic activity to antihypertensive drugs using a mental stress test in hypertensive patients and to determine the effects of antihypertensive drugs on the sympathetic activitymediated hemodynamic response to mental stress. Hypertensive patients were divided into three groups according to the type of drug(s) being taken: a calcium antagonist group, an angiotensin II receptor blocker group, and a combination therapy group of calcium antagonists and angiotensin II receptor blockers. The Stroop color-word conflict test was applied as a mental stress test and hemodynamic responses to mental stress were measured, including blood pressure, pulse rate, and skin blood flow. Elevation of blood pressure by mental stress was suppressed in the combination therapy group compared with the calcium antagonist group. Reduction of skin blood flow by mental stress was suppressed in both the angiotensin II blocker group and the combination therapy group compared with the calcium antagonist group. In conclusion, skin blood flow can be a useful tool to evaluate sympathetic activity and combination therapy with calcium antagonists and angiotensin II receptor blockers were the most useful therapy for suppressing the hemodynamic response to mental stress.展开更多
Aims: Bathing in deep, Japanese-style bathtubs is associated with high rates of sudden death in the elderly in Japan. The predominant causes of death in such cases are cardiovascular events and drowning. Blood pressur...Aims: Bathing in deep, Japanese-style bathtubs is associated with high rates of sudden death in the elderly in Japan. The predominant causes of death in such cases are cardiovascular events and drowning. Blood pressure changes induced by water pressure and high temperature during bathing may be an important cause of these accidents. Therefore, we investigated the changes in blood pressure, heart rate, and oxygen saturation (SpO2) before and after bathing in elderly Japanese individuals. Methods: Forty-eight elderly (average age, 86.4 ± 7.5 years) persons were enrolled in this study. Results: Changes in systolic blood pressure after bathing correlated negatively with baseline blood pressure before bathing, and participants with baseline systolic blood pressures of <125 mmHg experienced a greater elevation in blood pressure while bathing. Pulse rate was significantly increased after bathing, and the change in pulse rate correlated negatively with the baseline values. SpO2 did not differ significantly during bathing, but changes in SpO2 correlated negatively with baseline values. Lean participants showed a more marked elevation of SpO2, and those with hypertension showed reduced SpO2. Conclusion: These data suggest that the disabled elderly with low blood pressure experience trends in cardiovascular response during bathing which differ from those of young persons.展开更多
文摘The present study was designed to clarify the roles of N-type and P/Q-type calcium channels in the increased sympathetic activity of spontaneously hypertensive rats (SHR/Izm). We also tested in SHR/Izm the contribution to increased vascular tone of α1A adrenoceptor-linked L-type calcium channels and α1B receptor-mediated calcium mobilization from the sarcoplasmic reticulum. Methods: Six-week-old SHR/Izm and Wistar-Kyoto rats (WKY/Izm) were used. A superior mesenteric arterial preparation was electrically stimulated before and after treatment with ω-conotoxin GVIa (N-type calcium channel blocker [CgTX]) and ω-agatoxinIVa (P/Q-type calcium channel blocker [AgaTX]). Pressor response to norepinephrine was measured before and after treatment with the α1A blocker WB-4101 and the α1B blocker chloroethyl clonidine (CEC). To determine the intracellular calcium store size, the effects of ryanodine on pressor response and caffeine-induced vascular contraction were also tested. Results: Norepinephrine overflow evoked by electrical stimulation was increased in SHR/Izm. CgTX but not AgaTX suppressed the increased NE overflow in SHR/Izm. WB-4101 suppressed the pressor response to norepinephrine in SHR/Izm but not WKY/Izm rats. CEC had no effects on pressor response to norepinephrine in both types of rats. Caffeine-induced contraction to a high potassium-induced maximal contraction ratio was reduced in SHR/Izm. The effect of ryanodine on pressor response was reduced in SHR/Izm. Conclusion: N-type calcium channels but not P/Q-type calcium channels play an important role in the increased sympathetic tone in SHR/ Izm. Although α1A adrenoceptor-linked L-type calcium channels contribute to the increased vascular tone, the intracellular calcium store size was reduced in SHR/Izm.
文摘The aim of this study was to clarify the response of sympathetic activity to antihypertensive drugs using a mental stress test in hypertensive patients and to determine the effects of antihypertensive drugs on the sympathetic activitymediated hemodynamic response to mental stress. Hypertensive patients were divided into three groups according to the type of drug(s) being taken: a calcium antagonist group, an angiotensin II receptor blocker group, and a combination therapy group of calcium antagonists and angiotensin II receptor blockers. The Stroop color-word conflict test was applied as a mental stress test and hemodynamic responses to mental stress were measured, including blood pressure, pulse rate, and skin blood flow. Elevation of blood pressure by mental stress was suppressed in the combination therapy group compared with the calcium antagonist group. Reduction of skin blood flow by mental stress was suppressed in both the angiotensin II blocker group and the combination therapy group compared with the calcium antagonist group. In conclusion, skin blood flow can be a useful tool to evaluate sympathetic activity and combination therapy with calcium antagonists and angiotensin II receptor blockers were the most useful therapy for suppressing the hemodynamic response to mental stress.
文摘Aims: Bathing in deep, Japanese-style bathtubs is associated with high rates of sudden death in the elderly in Japan. The predominant causes of death in such cases are cardiovascular events and drowning. Blood pressure changes induced by water pressure and high temperature during bathing may be an important cause of these accidents. Therefore, we investigated the changes in blood pressure, heart rate, and oxygen saturation (SpO2) before and after bathing in elderly Japanese individuals. Methods: Forty-eight elderly (average age, 86.4 ± 7.5 years) persons were enrolled in this study. Results: Changes in systolic blood pressure after bathing correlated negatively with baseline blood pressure before bathing, and participants with baseline systolic blood pressures of <125 mmHg experienced a greater elevation in blood pressure while bathing. Pulse rate was significantly increased after bathing, and the change in pulse rate correlated negatively with the baseline values. SpO2 did not differ significantly during bathing, but changes in SpO2 correlated negatively with baseline values. Lean participants showed a more marked elevation of SpO2, and those with hypertension showed reduced SpO2. Conclusion: These data suggest that the disabled elderly with low blood pressure experience trends in cardiovascular response during bathing which differ from those of young persons.
