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...

Antihypertensive drug treatment is capable of aggravating angina pectoris in hypertensive patients with coronary artery disease. The complication appears to be due to different hemodynamic mechanisms. Angina pectoris caused by hydralazine may result not only from a reduction in aortic perfusion pressure but also from increases in cardiac output and pulse rate which the drug produces. Coronary i...

We studied the effects of intracoronary injection of nicotine and acetylcholine on coronary blood flow in nine conscious calves chronically instrumented to measure coronary blood flow, left ventricular (LV) and mean arterial pressure, LV dP/dt, and heart rate. Nicotine (5 micrograms/kg i.c.) elicited a biphasic response in coronary blood flow consisting of an initial vasoconstriction (phase 1; ...

The role of the sympathetic nervous system in 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol)-induced cardiovascular responses in urethane-anesthetized, normotensive rats was evaluated. Tempol caused dose-dependent (30-300 micromol/kg iv) decreases in renal sympathetic nerve activity (RSNA), mean arterial blood pressure (MAP), and heart rate (HR). Similar responses were obtained after sino...

We investigated the effects of low ouabain concentrations on systolic (SAP) and diastolic (DAP) arterial pressures and on pressor reactivity in 3-month-old male spontaneously hypertensive rats (SHR). Arterial blood pressure (BP) and pressor reactivity to phenylephrine (PHE) were investigated before and after 0.18 microg/kg ouabain administration (N = 6). The influence of hexamethonium (N = 6), ...

Sympathetic regulation of periodontal ligament blood flow (PLBF) is well-attested; however, vasodilator responses mediated by parasympathetic nerve fibers have yet to be conclusively demonstrated in the periodontal ligament (PL). The present study was designed to determine whether parasympathetic vasodilator mechanisms do or do not exist in the cat PL. In our cats, the cervical sympathetic trun...

introduction: world health organization (who) introduced hypertension as an epidemic in developing countries. however, hypertension is adequately controlled in only 12.5% of patients.  the aim of this study was to evaluate the relationship between ramadan fasting and mean arterial pressure (map). methods: this clinical, observational study was carried out at medical o.p.d of jinnah medical coll...

We investigated the effects of low ouabain concentrations on systolic (SAP) and diastolic (DAP) arterial pressures and on pressor reactivity in 3-month-old male spontaneously hypertensive rats (SHR). Arterial blood pressure (BP) and pressor reactivity to phenylephrine (PHE) were investigated before and after 0.18 μg/kg ouabain administration (N = 6). The influence of hexamethonium (N = 6), canr...

We determined the contributions of angiotensin II type 1 receptor (AT1) stimulation, adrenergic stimulation, and autonomic activation to pressure overload-induced c- fos expression in the adult rat heart in vivo. c- fos expression was increased in pressure-overloaded hearts created by aortic banding compared with sham-operated rats (458 ± 100% vs. sham, P < 0.05). GR-138950, a selective AT1 ant...