Hiromi Abeta

Kinins contribute to the improvement of insulin sensitivity during treatment with angiotensin converting enzyme inhibitor.

Although angiotensin converting enzyme inhibitors and alpha 1-blockers have been reported to improve insulin sensitivity, their mechanisms of action have not been elucidated. To investigate the role of kinins in insulin sensitivity, we treated 4-week-old spontaneously hypertensive rats with either an angiotensin converting enzyme inhibitor (enalapril), an alpha 1-blocker (doxazosin), or an angiotensin II antagonist (losartan) for 3 weeks. A control group received no drugs. In addition, 18 rats treated with enalapril or doxazosin received a simultaneous administration of a kinin antagonist (Hoe 140). Glucose clamp testing was performed in each group. Enalapril (128 +/- 1 mmHg) and doxazosin (132 +/- 2 mmHg) decreased mean blood pressure compared with control levels (148 +/- 1 mmHg) (P < .01). The glucose requirement for the clamp test during the administration of enalapril (25.8 +/- 0.5 mg/kg per minute) or doxazosin (28.6 +/- 0.7 mg/kg per minute) was higher than that of the control group (19.8 +/- 0.5 mg/kg per minute) (P < .05). Although Hoe 140 did not alter the glucose requirement of doxazosin (27.8 +/- 0.5 mg/kg per minute), it decreased that of enalapril (22.6 +/- 0.9 mg/kg per minute) (P < .05) without affecting the changes in mean blood pressure induced by enalapril. In addition, losartan decreased mean blood pressure but did not affect the glucose requirement. Thus, the improvement in insulin sensitivity produced by an angiotensin converting enzyme inhibitor is mostly dependent on kinins but not on angiotensin II antagonism, and an alpha 1-blocker improves insulin sensitivity irrespective of kinins.

Blood pressure response to hyperinsulinemia in salt-sensitive and salt-resistant rats.

We investigated the role of insulin in salt-sensitive hypertension in Dahl salt-sensitive and salt-resistant rats. The rats were kept in metabolic cages, and sodium intake and urinary sodium excretion were measured. In salt-sensitive rats receiving a 0.3% NaCl diet, sodium retention was significantly greater at weeks 1 and 2 in rats that received an insulin infusion than in those receiving a saline infusion. Mean arterial blood pressure and plasma norepinephrine levels were significantly higher at week 3 in insulin-treated rats than in saline-treated rats (mean arterial pressure, 137 +/- 3 mm Hg versus 119 +/- 3 mm Hg, p < 0.05; plasma norepinephrine, 0.40 +/- 0.02 ng/ml versus 0.27 +/- 0.01 ng/ml, p < 0.05). Insulin did not influence sodium retention, mean arterial pressure, or plasma norepinephrine in salt-resistant rats. Coadministration of an alpha-blocker (bunazosin, 10 mg/kg per day for 3 weeks) in salt-sensitive rats abolished the insulin-induced elevations in mean arterial pressure and sodium retention. When salt-sensitive rats were fed a low salt diet (0.03% NaCl), insulin did not raise mean arterial pressure. Thus, insulin elevated blood pressure only in the salt-sensitive model. The sympathetic nervous system and sodium retention in the early phase of insulin overload may contribute to elevation of mean arterial pressure in this model.

Oral peppermint oil is a useful antispasmodic for double-contrast barium meal examination

Background and Aim:  Intraluminally administered peppermint oil (PO) is reportedly a safe and useful antispasmodic for gastroscopy, colonoscopy and double‐contrast barium enema. The aim of this study was to examine the efficacy of oral PO for double‐contrast barium meal examination (DCBM) without other antispasmodics.