Enhanced protein synthesis in the renal arteries of genetically hypertensive rats: its possible role in causing hypertension.

A study was made of the vascular protein synthesis in young, genetically hypertensive rats, mainly in their renal arteries. Some of the rats were treated either with 3.5 mg/kg of phenoxybenzamine (POB) or with 4 mg/kg of propranolol twice daily, from 6 to 8 weeks of age. 3H-proline was injected intravenously into each rat before sacrifice to analyse the in vivo incorporation rates of tritiated proline into the vascular collagen and vascular non-collagenous proteins. Evidence has been presented that: (1) the rates of incorporation of 3H-proline into collagen and non-collagenous proteins of the renal arteries in spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) were greater than those in normotensive Wistar Kyoto rats (WKY); (2) the administration of POB decreased incorporation of 3H-proline into the collagen and non-collagenous proteins of the renal arteries concomitant with a reduction of blood pressure in every rat strain; (3) the administration of propranolol failed to decrease the incorporation of 3H-proline into these connective tissue proteins in the renal arteries and this drug did not reduce blood pressure in every rat strain; (4) the incorporation rates of 3H-proline into these protein fractions in hearts were similar in every rat strain which received any drug treatment. These results indicate that an increased synthesis of collagen and non-collagenous proteins in the renal arteries of young SHR and SHRSP rats participates in the pathogenesis of spontaneous hypertension in the early hypertensive stage.