​The autoregulation of blood flow in the active tissues is partly achieved locally by metabolites accumulated in these tissues. The contributions of different metabolites in this autoregulation are suggested in the following statements:
A. The accumulation of K⁺ locally in active tissues has vasoconstrictor activity.
B. The increase in osmolality in active tissues causes vasoconstriction.
C. The accumulation of lactate in active tissues may contribute to vasoconstriction.
D. The hypoxia-inducible factor-1α (HIF-1α) produced due to local fall in O₂ tension in active tissues, initiates the production of different vasodilatory substances.
E. Histamine released from the damaged cells of active tissues increases capillary permeability.
Choose the option with both correct statements:​

Correct option is D

Explanation-

Autoregulation is the process by which blood vessels maintain a relatively constant blood flow despite changes in perfusion pressure. In active tissues, local metabolic changes play a key role.

Statement A- The accumulation of K⁺ locally in active tissues has vasoconstrictor activity   - Incorrect.
K⁺ (Potassium ions) released during muscle activity cause vasodilation, not vasoconstriction.
Mechanism: Mild increases in extracellular K⁺ can hyperpolarize vascular smooth muscle, leading to relaxation.
Statement B-  The increase in osmolality in active tissues causes vasoconstriction    -   Incorrect.
Increased osmolality typically causes vasodilation as it signals high metabolic activity. This helps increase blood flow to the area.
Statement C -  The accumulation of lactate in active tissues may contribute to vasoconstriction    -   Incorrect.
Lactate, produced during anaerobic metabolism, is a vasodilator, not a vasoconstrictor.
It helps in increasing blood flow to meet oxygen demands.
Statement D - The hypoxia-inducible factor-1α (HIF-1α) produced due to local fall in O₂ tension in active tissues, initiates the production of different vasodilatory substances  -  Correct.
HIF-1α is a transcription factor activated under hypoxic conditions. It stimulates production of VEGF, nitric oxide, and other vasodilators to improve oxygen delivery.
Statement E - Histamine released from the damaged cells of active tissues increases capillary permeability  -  Correct.
Histamine increases capillary permeability and causes vasodilation, facilitating immune cell access and nutrient delivery. It plays a role in inflammation and tissue response.

Correct statement - D and E

So, the correct answer is option d - D and E