Pharmacological effects of drugs on the pulmonary circulation in man

The effect of drugs on the human pulmonary circulation has been reviewed in light of newer physiological mechanisms shown to regulate that vascular bed. If one takes the measurement of pulmonary vascular resistance (PVR) as the basic information required, surprisingly few drugs have been adequately evaluated in man. Even PVR may be affected by changes other than those produced by active vasomotion, often making its interpretation difficult. The effects of the hydrostatic gradients of pulmonary arterial and venous pressures on PVR have been discussed. Most of the evaluations of vasodilator drugs have been made in patients with pulmonary hypertension due to mitral stenosis. The suitability of these patients for such studies has lately been questioned by the finding that the increased PVR may be due to perivascular edema rather than active vasoconstriction. Most information is available on the effects of acetylcholine, although an adequate literature exists for isoproterenol, aminophylline, and bradykinin. Studies of vasoconstrictor agents have been made in subjects with normal pulmonary circulation. Although serotonin produces an unequivocal rise of PVR in animals, it does nat do so in man. The effects of the commonly used drug, norepinephrine, is still unsettled, while angiotensin and bretylium tosylate cause a clear increase in PVR.