Pro-collagen peptides in essential hypertension and its relation to cardiac structure and functions before and after antihypertensive therapy

ABSTRACT

A significant increase in fibrillar collagen content, type I and type III, has been observed in the cardiac ventricles of both animals and humans with arterial hypertension. The serum concentrations of procollagen type I carboxy terminal peptide [PIP] and procollagen type III amino terminal peptide [PIIIP] have been proposed as a useful markers of collagen types I and III synthesis. We evaluated fibrogenic activity in patients with essential hypertension by measuring serum concentrations of PIP and PIIIP as markers of tissue synthesis of collagen type I and type III, and its relation to parameters of left ventricular [LV] structure and functions in those patients. The effect of treatment with ACE inhibitor [captopril] for 6 months on serum concentrations of both PIP and PIIIP was also studied. The study included 79 patients with newly diagnosed mild to moderate hypertension and 50 normotensive subjects. Ages ranged between 35 to 60 years. Careful blood pressure measurement was obtained in all subjects. M-mode, two dimensional, and pulsed Doppler were performed to get baseline LV anatomy and function. Serum PIP and PIIIP were measured by radioimmunoassay. Both echocardiography and biochemical studies were repeated for all hypertensives after 6 months treatment with captopril. Serum PIP and PIIIP were significantly higher in hypertensive patients compared with normotensive subjects. PIP was 258 +/- 57mg/L in hypertensives vs. 167 +/- 70mg/L in normotensives. PIIIP was 3.73 +/- 2.2mg/L in hypertensives vs. 1.9 +/- 1.4mg/L in normotensives. In addition, PIP and PIIIP were significantly higher in hypertensives with LV hypertrophy [LVH] than those with normal LV mass. Moreover, serum concentration of PIP was directly correlated with LV mass index. On the other hand, PIIIP was inversely correlated with VE/VA ratio. After treatment, significant echocardiographic and biochemical improvements were observed. LVH regressed in 13 out of 68 patients [19%], LV mass index was normalized in 17 out of 58 patients [29%], and diastolic dysfunction was normalized in 10 out of 44 patients [23%]. Serum PIP and PIIIP were significantly reduced in hypertensives. Serum concentrations of both PIP and PIIIP are significantly increased in hypertensives and this was more pronounced among patients with LVH. This was correlated with structural and functional LV changes in the form of LVH and diastolic dysfunction. All changes demonstrated significant improvement after treatment with captopril