Effect of calcium and calcium blockers in hypertension

Calcium is important in the maintenance of arterial smooth muscle function and its alteration from normal may predispose to atherogenesis and hypertension. Slow channel inhibitors such as nifedipine and calcium salts have been used separately to modulate arterial calcium in patients with hypertension. This study included 41 patients with essential hypertension, of whom 29 responded to calcium gluconate therapy (9.8/6.3 mmHg) and the remaining 12 (group B) showed either no response or a rise in blood pressure. Combined administration of calcium and nifedipine in responders (29 cases, group A) in a single-blind, placebo-controlled manner showed a further substantial decrease (9.6/3.2 mmHg) in pressure compared with pressures during placebo administration in both short- as well as long-term administration in group B patients. Although it is difficult to predict the positive role of calcium in hypertension, non-obese females with increased salt intake show a greater response to calcium therapy. It is possible that calcium salts plus calcium blocker therapy can further reduce the blood pressure in a particular subset of hypertensives. However, this needs further confirmation in a larger study.

Effect of diet and weight reduction in hypertension

Weight reduction by a low-energy diet and a high-polyunsaturates-, fiber- and potassium-rich diet may be independently useful to hypertensives. To study the effect of such diets, 416 hypertensives were randomized to either a low-energy cardiovasoprotective (CVP) diet (Group A; n = 106), a low-energy usual diet (Group B; n = 104), an optimal-energy CVP diet (Group C; n = 104), or an optimal-energy, usual pre-experimental diet (Group D; n = 102) plus drug therapy in a single-blind and controlled fashion. Groups A and B received significant (p less than 0.02) fewer calories per day than Groups C and D. Groups A and C also received significantly (p less than 0.02) more calories per amount of complex carbohydrates, polyunsaturates, potassium, and magnesium than did Groups B and D. Dietary compliance and drug intake was checked weekly. After 3 months, there was a significant fall in mean serum cholesterol (p less than 0.01) and mean serum triglycerides (p less than 0.05) in Group A compared with Group D. Group A and B patients had a loss of around 10kg of mean body weight, with no weight change seen in Group D. Weight loss was associated with a significant fall in systolic and diastolic pressures in both Group A (22/18mmHg) and Group B (16/13mmHg) compared with Group D at the end of the study. Group C patients also showed a significant fall in pressure (13/10mmHg) compared with Group D. Drug therapy, exercise, and salt intake were similar in all the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary modulators of blood pressure in hypertension

To study the role of diet, 197 patients of essential hypertension were randomized to either experimental diet (group A, 97 cases) or normal diet (group B, 100 cases) with diuretics given to both the groups. The age varied between 25 and 65 years and 154 were males. The study diet included a significantly higher content of potassium (K), magnesium (Mg), calcium (Ca), polyunsaturated fat, and complex carbohydrates compared to the normal diet. At entry to the study, age, sex, risk factors, mean blood pressures, mean serum Mg, K, Ca, and Na, and drug therapy were comparable in both groups. After 1 year of follow-up, there were significantly fewer patients with resistant hypertension in group A (5) than in group B (17). Mean systolic (148.22 +/- 10.1 mm Hg) and diastolic (90.2 +/- 4.84 mm Hg) pressures in group A were lowered compared to mean systolic (160 +/- 12.0 mm Hg) and diastolic (103.3 +/- 5.8 mm Hg) pressures in group B and initial mean systolic (152.2 +/- 12.8 mm Hg) and diastolic (99.8 +/- 7.2 mm Hg) pressures. Mean serum magnesium (1.86 +/- 9.22 mEq/l) and potassium (4.86 +/- 0.39 mEq/l) levels in group A were significantly higher compared to mean levels of 1.56 +/- 0.11 and 4.0 +/- 0.29 mEq/l, respectively, in group B. However compared to initial levels, K and Mg showed no significant changes in groups A and B. There was a significantly lower incidence of complications in group A (58) compared to group B (100). It is possible that a diet low in Na/K ratio and rich in complex carbohydrates, polyunsaturates, K and Mg may cause a significant reduction in blood pressure and its complications.

Cardiovascular manifestations of aluminium phosphide intoxication

Aluminium phosphide (ALP) a major suicidal agent in the developing countries is freely available as grain fumigant. It is highly toxic to lungs, heart and blood vessels causing pulmonary oedema, shock and arrhythmias. There is massive focal myocardial damage resulting in raised cardiac enzymes. Clinical manifestations were nausea and vomiting (32), dyspnoea and palpitations (25 each), cyanosis (12), hypotension (12) and shock (15). Cardiac arrhythmias were present in 28 cases and hypermagnesaemia in 13 patients. Mean serum magnesium level (1.95 +/- 0.2O, mEq/L) was significantly raised compared to mean magnesium level in control subjects (1.62 +/- 0.23 mEq/L). Hypermagnesaemia occurs due to myocardial and liver damage. Out of 32 cases studied, 22 died 18 within 24 hours of ALP ingestion. Thirty two cases of ALP were studied.

Is verapamil a better magnesium agonist rather than a calcium antagonist? A hypothesis?

Mg and verapamil have similar effects on the cardiovascular system. Both the agents have been successfully used for the treatment of hypertension and protection of the ischaemic myocardium. The exact mechanism of action of calcium blocking drugs including verapamil is unknown. It is proposed that verapamil stimulates the Mg-carrying transport system and Mg diffusion in the cell so that Mg influx is enhanced. This in turn causes suppression of the slow inward Ca current and fast inward Na current resulting into decreased transport of Ca and Na. Verapamil possibly also influences outward K and Mg currents and alter the shape and duration of the action potential. Since Mg ions maintain the structural and functional integrity of the cardiovascular system, therefore Mg mediated mechanisms of action for verapamil appears to be more logical.

Karyotypic analysis of Cajanus, Atylosia, and Rhynchosia species

Somatic chromosomes of two cultivais of Cajanus cajan, eight species of Atylosia (A. albicans, A. cajanifolia, A. lineata, A. platycarpa, A. scarabaeoides, A. serica, A. trinervia and A. volubilis), and of Rhynchosia rothii were analysed. All species had 2n=22. Eight of the 10 species studied had two pairs of satchromosomes while A. scarabaeoides and A. sericea had only one sat-chromosome pair. Based on relative chromosome length (L%), arm ratio (pa-value) and presence or absence of secondary constriction, a karyotype formula for each species was formulated. Based on these parameters the chromosome pairs could also be assigned to groups ranging from 8 to 10 in different species. Except for the asymmetrical karyotype of A. albicans, the other species had rather moderately symmetrical karyotypes.

Cytogenetics of F1 hybrids between Cajanus and Atylosia species and its phylogenetic implications

Cytogenetic relationships between two cultivars of Cajanus cajan and six species of Atylosia were investigated. Of the 12 cross combinations obtained, only seven could be studied. Meiotic chromosome pairing, pollen and ovule fertility in parental species and four F1 hybrids were near normal. Some meiotic abnormalities were observed in the Fls: A. lineata x A. scarabaeoides, A. scarabaeoides x A. sericea and C. cajan (UPAS 120) x A. trinervia, indicating varying degrees of chromosomal and genic differences between these species. These observations suggested that A. cajanifolia is the closest wild relative of C. cajan, followed by A. scarabaeoides, A. albicans and A. trinervia. Among the Atylosia species, A. sericea was closer to A. scarabaeoides than to A. lineata.