Summary:The evidence linking magnesium disorders with the pathogenesis and treatment of various cardiovascular diseases will be reviewed.

The pharmacological actions of a diuretic drug, fenquizone have been investigated and its effects compared with well characterized diuretics in rats, mice and rabbits. Changes in sodium and potassium excretion and urine volume were similar in magnitude and duration to those of the thiazide diuretics over dose range 0.05-100 mg kg-'. Free water clearance in rabbits wasdecreased indicatingan action at thecortical dilutingsite in the nephron and since free water reabsorption was relatively unaffected it appears unlikely to have actions at other sites. Calcium and phosphate excretion studies also suggested that the predominant effects arethose occurring at the cortical diluting segment of the nephron. Additional parametersnot affected by the drug were blood flow to the cortex and medulla of the kidney (and other major organs), plasma glucose concentration and plasma urate concentration.

Most PDVSs had numerous characteristics in common however no two PDVSs were identical. Characteristics involved in the creation of service demand such as number and type of referral sources, are more likely to be associated with PDVS continuation.