Inotropic action of hydroxylated chlorpromazine metabolites and related compounds

Induction of hypertension and peripheral inflammation by reduction of extracellular superoxide dismutase in the central nervous system

The circumventricular organs (CVOs) lack a well-formed blood-brain barrier and produce superoxide in response to angiotensin II and other hypertensive stimuli. This increase in central superoxide has been implicated in the regulation of blood pressure. The extracellular superoxide dismutase (SOD3) is highly expressed in cells associated with CVOs and particularly with tanycytes lining this region. To understand the role of SOD3 in the CVOs in blood pressure regulation, we performed intracerebroventricular injection an adenovirus encoding Cre-recombinase (5x10(8) particles per milliliter) in mice with loxP sites flanking the SOD3 coding region (SOD3(loxp/loxp) mice). An adenovirus encoding red-fluorescent protein was injected as a control. Deletion of CVO SOD3 increased baseline blood pressure modestly and markedly augmented the hypertensive response to low-dose angiotensin II (140 ng/kg per day), whereas intracerebroventricular injection of adenovirus encoding red-fluorescent protein had minimal effects on these parameters. Adenovirus encoding Cre-recombinase-treated mice exhibited increased sympathetic modulation of heart rate and blood pressure variability, increased vascular superoxide production, and T-cell activation as characterized by increased circulating CD69(+)/CD3(+) cells. Deletion of CVO SOD3 also markedly increased vascular T-cell and leukocyte infiltration caused by angiotensin II. We conclude that SOD3 in the CVO plays a critical role in the regulation of blood pressure, and its loss promotes T-cell activation and vascular inflammation, in part by modulating sympathetic outflow. These findings provide insight into how central signals produce vascular inflammation in response to hypertensive stimuli, such as angiotensin II.

Effects of chlorpromazine and its dihydroxy metabolite on calcium movement and electrical activity in superior cervical ganglia

Chlorpromazine (CPZ) binding and the binding to isolated guinea pig superior cervical of a toxic metabolite 7,8-dihydroxychlorpromazine (7,8-diOH-CPZ) were studied under resting and potassium-stimulated conditions. Maximal binding occurred more rapidly in high potassium, with binding of CPZ 10 fold higher than that of 7,8-diOH-CPZ. However, in low potassium media 50% of bound CPZ and 60% of 7,8-diOH-CPZ was retained following a 240-min washout procedure. When the washout of the drugs from the tissue was studied, release was found to be more extensive in high potassium washout media. Under resting conditions, at 10 microM CPZ or 7,8-diOH-CPZ, calcium accumulation by ganglia decreased but increased at higher drug concentrations. Calcium (Ca) uptake increased with both drugs in high potassium medium. Ca efflux from the tissue was accelerated by both phenothiazines in a dose-dependent fashion. CPZ blocked ganglionic transmission at 20 microM while 7,8-diOH-CPZ (up to 100 microM) increased ganglionic potential amplitude. Thus CPZ and 7,8-diOH-CPZ differ in binding to ganglia and in effects on ganglionic transmission.

Carnitine transport in isolated adult rat heart myocytes and the effect of 7,8-diOH chlorpromazine

We studied the carnitine transport system in isolated adult rat heart myocytes able to tolerate physiological concentrations of calcium. Carnitine uptake occurred against a concentration gradient and was inhibited by 2,4-dinitrophenol (2,4-DNP). The transport system had a Km of 60 microM and a Vmax of 110 pmol/mg protein per hour. The carnitine precursor deoxycarnitine, acetylcarnitine, and both the D and L isomers were effective inhibitors of uptake. The transport of carnitine was not dependent on sodium ions, but was stimulated by decreasing concentrations of calcium ions. Decreased uptake was observed in the presence of beta-adrenergic agonists and antagonists, dibutyrl cyclic AMP, local anesthetics, and ouabain. No significant alteration of uptake was effected by atropine, carbachol or a variety of tricyclic agents. The auto-oxidation product of 7,8-dihydroxychlorpromazine (7,8-diOH CPZ) decreased carnitine efflux from myocytes, which were highly permeable to low molecular weight compounds. We found that this effect was not substrate specific, and is discussed as possibly resulting from a change in the arrangement or state of polymerization of subcellular structural components.