ONE of the few observations made in hypertension upon which there is almost universal agreement is the increased response of the blood pressure to pressor drugs. It is found in nearly all types of hypertension, both experimentally and clinical.>9 Nevertheless, the mechanisms responsible for it have not been adequately investigated. I have studied the vascular reactivity in rabbits, comparing th...

This study records the gastric secretory response, using the Kay augmented histamine test, and compares "medical" vagotomy with atropine and hexamethonium with "surgical" vagotomy. The results suggest that it may be of value in predicting the effect of vagotomy with gastrojejunostomy.

Metformin lowers blood pressure in humans and in experimental animal models. To determine the mechanism of acute metformin-induced hypotension, we measured changes in mean arterial pressure (MAP) and heart rate (HR) during metformin alone (0, 10, 50, 100 mg/kg i.v.; n = 10) and during concomitant alpha adrenergic (phentolamine, 5 mg/kg; n = 5), beta adrenergic (propranolol, 3 mg/kg; n = 6), mus...

The neuronal mechanism by which distension of the colon triggers peristalsis and the propulsion of colonic contents is incompletely understood. In this study, we used video imaging and spatiotemporal mapping techniques to investigate the neuroneuronal mechanisms underlying peristalsis in isolated guinea pig distal colon. In direct contrast to previous studies, we found that hexamethonium (100 m...

Parasympathetic withdrawal plays an important role in the autonomic dysfunctions in hypertension. Since hyperpolarizing, voltage-sensitive K(+) channels (K V) hamper transmitter release, elevated K V-activity may explain the disturbed vagal control of heart rate (HR) in hypertension. Here, the K V inhibitor 3,4-diaminopyridine was used to demonstrate the impact of K V on autonomic HR control. C...

The effect of vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase-activating peptide-38 (PACAP-38), and PACAP-27 on the release of serotonin (5-HT) into the intestinal lumen and the portal circulation was studied by using in vivo isolated vascularly and luminally perfused rat duodenum. 5-HT levels were determined by HPLC. VIP, PACAP-38, and PACAP-27 reduced the luminal release ...