Effects of norepinephrine infusion on systemic hemodynamics and plasma 6-keto-prostaglandin F1 alpha in normotensive subjects and patients with essential hypertension

Effect of cyclooxygenase inhibition on the inspiratory muscle metaboreflex-induced cardiovascular consequences in men

Inspiratory muscle metaboreflex activation increases mean arterial pressure (MAP) and limb vascular resistance (LVR) and decreases limb blood flow (Q̇_L). Cyclooxygenase (COX) inhibition has been found to attenuate limb skeletal muscle metaboreflex-induced increases in muscle sympathetic nerve activity. We hypothesized that compared with placebo (PLA), COX inhibition would attenuate inspiratory muscle metaboreflex-induced 1) increases in MAP and LVR and 2) decreases in Q̇_L Seven men (22 ± 1 yr) were recruited and orally consumed ibuprofen (IB; 10 mg/kg) or PLA 90 min before performing the cold pressor test (CPT) for 2 min and inspiratory resistive breathing task (IRBT) for 14.9 ± 2.0 min at 65% of maximal inspiratory pressure. Breathing frequency was 20 breaths/min with a 50% duty cycle during the IRBTs. MAP was measured via automated oscillometry, Q̇_L was determined via Doppler ultrasound, and LVR was calculated as MAP divided by Q̇_L Electromyography was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to greater increases (P = 0.02) in 6-keto-prostaglandin-F_1α with PLA compared with IB. IB, compared with PLA, led to greater (P < 0.01) increases in MAP (IB: 17 ± 7 mmHg vs. PLA: 8 ± 5 mmHg) and LVR (IB: 69 ± 28% vs. PLA: 52 ± 22%) at the final minute of the 65% IRBT. The decrease in Q̇_L was not different (P = 0.72) between IB (-28 ± 11%) and PLA (-27 ± 9%) at the final minute. The increase in MAP during the CPT was not different (P = 0.87) between IB (25 ± 11 mmHg) and PLA (24 ± 6 mmHg). Contrary to our hypotheses, COX inhibition led to greater inspiratory muscle metaboreflex-induced increases in MAP and LVR.NEW & NOTEWORTHY Cyclooxygenase (COX) products play a role in activating the muscle metaboreflex. It is not known whether COX products contribute to the inspiratory muscle metaboreflex. Herein, we demonstrate that COX inhibition led to greater increases in blood pressure and limb vascular resistance compared with placebo during inspiratory muscle metaboreflex activation.

Urinary excretion of 2,3-dinor-6-keto-PGF1 alpha and 11-dehydro-TXB2 by the gravid spontaneously hypertensive rat

Little is known about the pathophysiological processes leading to superimposed preeclampsia. We present an animal model where the uteroplacental blood flow in spontaneously hypertensive rats (SHR) was reduced by a silver clip. Thus, a superimposed preeclampsia-like syndrome could be studied under defined conditions. Urinary excretion of 2,3-dinor-6-keto PGF1 alpha and 11-dehydro-TxB2 were measured by enzyme immunoassays at day 16 and 20 of pregnancy. In gravid, sham-operated animals excretion of 2,3-dinor-6-keto-PGF1 alpha was largely elevated compared to non gravid control animals (day 16: 1259 vs. 258 ng/kg 24h; day 20: 471 vs. 269 ng/kg.24h). However, in the gravid rats with reduced uteroplacental blood flow urinary excretion of 2,3-dinor-6-keto-PGF1 alpha decreased to non gravid levels (day 16: 335 ng/kg.24h; day 20: 238 ng/kg.24h). By antihypertensive therapy with dihydralazin this effect was largely abolished. Only minor alterations were found in the excretion of 11-dehydro-TxB2. Our findings suggest, that a reduction of uteroplacental blood flow in the spontaneously hypertensive rat decreases the systemic prostacyclin synthesis.

Implication of thromboxane in the pathogenesis of Kawasaki disease and a suggestion for using novel thromboxane synthetase inhibitors in its treatment

Kawasaki disease, a mucocutaneous lymph node syndrome predominantly prevalent in children, presents with coronary artery aneurysms and thrombocytosis, and investigators have suggested use of anticoagulants in addition to platelet inhibiting drugs. In Kawasaki disease, hypersensitivity reactions due to antigen/antibody complexes (Arthus type III) may damage the vessel wall and induce arteritis, and antigens may be of microbial or viral origin. Since thromboxane has been implicated in the pathogenesis of Kawasaki disease, I suggest use of ginger and carbon dioxide, novel thromboxane synthetase inhibitors. Thromboxane synthetase inhibitors may act as anticoagulants, platelet inhibitors, anti-inflammatory agents, and agents with both antimicrobial and antiviral activity.

Ginger: inhibition of thromboxane synthetase and stimulation of prostacyclin: relevance for medicine and psychiatry

Ginger, the common spice, has recently been found to act as a potent inhibitor of thromboxane synthetase, raising levels of prostacyclin, without a concomitant rise in PGE2 or PGF2 alpha. Indications for use of ginger to replace either thromboxane inhibitors having serious side effects or prostacyclin are given.