Singh R B, Singh N K, Mehta P J, Rastogi S S
Medical Hospital and Research Centre, Moradabad, India.
Acta Cardiol. 1987;42(6):445-67.
Albert Szent-Gyorgyi around 30 years ago proposed that "ions were the powerful tools of life as it developed in oceans". The purpose of this fundamental concept was to divert the attention of investigators towards the basic role of cations such as Na, K, Ca and Mg in muscle contraction. There is now sufficient evidence to support this prediction. Until recently the strongest evidence pointed to a positive relationship between raised Ca and blood pressure. More recent evidence claimed that increased dietary Ca can lower blood pressure and populations taking lowered dietary Ca, have a higher incidence of hypertension. It has been suggested that in susceptible persons, in the presence of high Na intake, Ca accumulation in the arterial cell becomes rapid due to impaired Na-Ca exchange causing an early rise in blood pressure. This is possibly due to abnormal handling of Ca by the smooth muscle cells in most forms of hypertension. Clinical experimental and epidemiologic studies showed that Ca not only mediates arterial smooth muscle contraction but excess of Ca can also cause an increase in peripheral vascular resistance leading to essential hypertension. Ca entry blockers such as verapamil and nifedipine which reduce the influx of Ca into the arterial smooth muscle cell have been successfully used in the management of these patients. The effect of Ca on blood pressure could be independent of other factors. Recent studies strongly favour a significant relationship between raised serum Ca and high blood pressure. Such a relationship has also been described between dietary Ca, 24 urinary Ca and high blood pressure. A large number of studies, particularly from the USA, contradicting the above view, suggest that the rate of Ca flux rather than the absolute quantity that enters the cell, is the deciding factor in arterial smooth muscle contraction. These investigators in the last 6 years have studied a large area of north America and suggested that Ca deficiency rather than an excess is the cause of hypertension. Persons consuming less than 300 mg Ca per day have 11-14% risk of developing hypertension compared to person taking 1200 mg per day of dietary Ca and exposed to only 3-6% risk.(ABSTRACT TRUNCATED AT 400 WORDS)
大约30年前，阿尔伯特·圣捷尔吉提出“离子是生命在海洋中发展时的有力工具”。这一基本概念的目的是将研究者的注意力转向阳离子如钠、钾、钙和镁在肌肉收缩中的基本作用。现在有足够的证据支持这一预测。直到最近，最有力的证据表明升高的钙与血压之间存在正相关。最近的证据称，增加饮食中的钙可以降低血压，而饮食中钙摄入量降低的人群患高血压的几率更高。有人提出，在易感人群中，在高钠摄入的情况下，由于钠钙交换受损，动脉细胞中的钙积累会迅速增加，导致血压早期升高。这可能是由于大多数形式的高血压中平滑肌细胞对钙的处理异常。临床实验和流行病学研究表明，钙不仅介导动脉平滑肌收缩，而且过量的钙还会导致外周血管阻力增加，从而引发原发性高血压。钙通道阻滞剂如维拉帕米和硝苯地平，可减少钙流入动脉平滑肌细胞，已成功用于治疗这些患者。钙对血压的影响可能独立于其他因素。最近的研究强烈支持血清钙升高与高血压之间存在显著关系。饮食中的钙、24小时尿钙与高血压之间也有这样的关系。大量研究，特别是来自美国的研究，与上述观点相矛盾，表明钙通量的速率而非进入细胞的绝对量，是动脉平滑肌收缩的决定因素。在过去6年里，这些研究者对北美大片地区进行了研究，并提出钙缺乏而非过量是高血压的病因。每天摄入钙少于300毫克的人患高血压的风险为11 - 14%，而每天摄入1200毫克饮食钙的人患高血压的风险仅为3 - 6%。（摘要截选至400字）
